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Jerusalem artichoke (Helianthus tuberosus L.) is a plant with considerable potential for energy generation due to its rapid growth, high biomass yield, and resistance to environmental stresses. The aim of this study was to determine the influence of the nitrogen fertilization strategy on the yield and energy balance in the production technology of Jerusalem artichoke (JA) in a perennial cropping system. The article presents the results of a three-year experiment which was conducted in Poland to determine the effect of different N rates (0, 50, 75, and 100 kg ha−1) supplied with mineral fertilizers and liquid digestate on the energy balance in the production of JA aerial biomass. The experiment had a randomized block design with three replications. The demand for energy in JA cultivation reached 16.2–26.3 (year 1) and 2.9–14.6 GJ ha−1 (years 2 and 3). Energy inputs in the cultivation technology were reduced by 17–19% (year 1) and 35–47% (years 2 and 3) when mineral fertilizers were replaced with digestate. Jerusalem artichoke yields were lowest in the technology without fertilization (12.5 Mg ha−1 DM). Dry matter yield increased significantly (by 43–55%) after the application of 75 kg N ha−1, regardless of fertilizer type. The energy output of biomass peaked (230.1 GJ ha−1) in response to a mineral fertilizer rate of 75 kg N ha−1. In turn, the highest energy gain (218.5 GJ ha−1) was noted after the application of digestate at a rate equivalent to 75 kg N ha–1. The energy efficiency ratio was highest in the technology without fertilization (20.1) and after the application of digestate at a rate equivalent to 75 kg N ha−1 (19.7). Regardless of the factors that limit agricultural production, the energy balance of JA biomass production was most favorable when JA was fertilized with digestate at a rate equivalent to 75 kg N ha−1. The results of this study may pave the way for future research on novel agronomic strategies for sustainable bioenergy production, including nutrient recycling. [ABSTRACT FROM AUTHOR]

This article presents the results of a three-year experiment (2018–2020) conducted at the Agricultural Experiment Station in Bałcyny (north-eastern Poland) with the aim of determining Jerusalem artichoke (JA) yields and the energy balance of biomass production in (i) a perennial cropping system (only aerial biomass was harvested each year) and (ii) an annual cropping system (both aerial biomass and tubers were harvested each year). When JA was grown as a perennial crop, the demand for energy reached 25.2 GJ ha−1 in the year of plantation establishment and 12.3–13.4 GJ ha−1 in the second and third year of production. The energy inputs associated with the annual cropping system were determined in the range of 31.4–37.1 GJ ha−1. Biomass yields were twice as high in the annual than in the perennial cropping system (20.98 vs. 10.30 Mg DM ha−1). Tuber yield accounted for 46% of the total yield. The energy output of JA biomass was 1.8 times higher in the annual than in the perennial cropping system (275.4 vs. 157.3 GJ ha−1). The average energy gain in JA cultivation ranged from 140 (perennial crop) to 241 GJ ha−1 (annual crop). The energy efficiency ratio of JA biomass production reached 7.7–13.3 in the perennial cropping system, and it was 20% lower in the annual cropping system. These results imply that when JA was grown as an annual crop, an increase in energy inputs associated with plantation establishment (tillage and planting) and the harvest and transport of tubers was not fully compensated by the energy output of tubers. [ABSTRACT FROM AUTHOR]

To explore the heating characteristics of a radiation air conditioning system, a radiation air conditioning system test bench was built, a 7-day intermittent operation test was conducted. The temperature and humidity of the air from two-stage fresh air unit, the heat output and efficiency of the air-source heat pump, as well as the energy use and efficiency ratio of the system were analyzed emphatically. The results show that under setting parameters, the stable supply air temperature and humidity of the two-stage fresh air are about 27 °C and 35%, respectively. The average heating capacity of the air source heat pump host is 4.5 kW, and the heating coefficient of performance (COPU) is 4.10. The power consumption of the radiation air conditioning system is 1.5 kW·h, and the system coefficient of performance (COPS) is 3.02. The results can provide reference for further optimization and promotion of the system. [ABSTRACT FROM AUTHOR]

Broadly defined climate protection is a powerful incentive in the search for environmentally friendly refrigeration technologies. Adsorption chillers are considered to be one such technology; however, their main disadvantages include a low cooling capacity, a low energy efficiency ratio (EER), and cyclic operation. Thus, a great deal of effort is being put into improving adsorption-chiller performance. In this paper, the influence of the spray angle, the number of nozzles, and the water flow rate through the nozzles on adsorption-chiller performance was investigated. Adsorption-chiller performance was investigated mainly in terms of the cooling capacity (CC), the energy efficiency ratio (EER), and the specific cooling power (SCP). The results indicated that the chiller's cooling capacity increased from about 210 W to 316 W and that the EER increased from 0.110 to 0.167 when the spray angle of the nozzles was increased from 90° to 120°. It was also reported that increasing the flow rate of water through the nozzles did not improve the average cooling capacity or the other performance parameters but resulted in more stable operation of the chiller. Additionally, using six nozzles instead of three improved the average cooling capacity and EER tenfold. [ABSTRACT FROM AUTHOR]

In order to improve the internal heat dissipation efficiency of the proton exchange membrane fuel cell, this paper designs and builds a set of fuel cell heat dissipation system experimental bench with a heat dissipation capacity of 15 kW based on the separated heat pipe technology, and investigates the heat dissipation characteristics of the HFE-7100 and ethylene glycol aqueous cooling medium under different condenser processes and different ambient temperatures. The results show that at an ambient temperature of 35 °C, under the same condenser flow arrangement, the two-phase heat dissipation efficiency of HFE-7100 is higher than that of glycol aqueous solution liquid cooling, and its heat dissipation and EER (Energy Efficiency Ratio) are increased by 81.2 %∼98.8 % and 68.2 %∼86.6 %, respectively. The best effect is achieved when the condenser is 3-process, with two-phase heat dissipation of 14.1 kW and EER of 20.5 kW/kW, which are 82.8 % and 68.9 % higher than liquid cooling, respectively. As the ambient temperature rises, the two-phase heat dissipation effect is further improved, and at 50 °C ambient temperature, the heat dissipation is 10.44 kW, which is 145 % higher than that of liquid cooling, and the EER is 15 kW/kW, which is 132 % higher.

Copyright of Energy Policy Journal / Polityka Energetyczna is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The control strategy is important for variable refrigerant flow (VRF) air conditioning system to realize energy saving and stable operation. In this work, the super‐heating degree (SHD) responsive control strategy was developed to dynamically adjust the respective SHD target value (ΔTe,tar) of indoor units so as to adapt to the variable cooling load. The capacity code (Ecode) is introduced into the control model to quantify the reference target value of SHD. To responsively adapt to variable cooling load, the correction target values of SHD based on discharge temperature and deviation of the outlet air temperature are introduced in the SHD model for operation protection of the compressor and the consistency of refrigerant distribution. The enthalpy difference analogy method is developed to estimate the performance of the VRF system including cooling capacity, electric power, and energy efficiency ratio (EER). The performance was tested under the conditions of different ΔTe,tar. Experimental results demonstrate that the ΔTe,tar is an important factor to determine the operation frequency, which affects cooling capacity, power, EER, and operation status of the system. The cooling capacity and electric power at the ΔTe,tar of 9°C was about 55.2% and 63.5% lower than those at the ΔTe,tar of 1°C, and the corresponding EER was improved by 22.6%. To further verify the SHD control strategy, the VRF system was tested by the responsive control model under the condition that Ecode and ΔTe,tar were constantly automatically adjusted and changed with the actual indoor ambient temperature. Experimental results demonstrate that the VRF system can achieve a good and uniform cooling effect and realize energy saving and stable operation according to the responsive super‐heating degree control.

Characterising the energy efficiency grades of machining systems (MS) is an effective analytical methodology or management tool that helps to establish the high energy-efficient MS. However, the current MS energy efficiency approaches still lack scientific and practical formulation strategies to addresses this issue due to its multi-source and variable energy consumption characteristics. Focusing on this challenge, a new concept of inherent energy efficiency (IEE), which is formed in the design and formation phases of the MS, is proposed. Meanwhile, a novel energy efficiency grade evaluation (EEGE) approach based on IEE is also presented. The proposed EEGE approach not only can evaluate the MS energy efficiency grades, but also can reveal the MS high energy-efficient intervals. According to the analysis of IEE in MS, the EEGE approach is developed in three steps: (i) the establishment of IEE evaluating indicator system from both inherent energy utilisation (IEU) and inherent specific energy (ISE), (ii) the acquisition of the IEE, and (iii) the development of a quantitative method for the EEGE in MS. Finally, a case study of energy efficiency grade evaluation and analysis for an XK714D CNC milling machining centre is examined, illustrating the practicability of the proposed method. [ABSTRACT FROM AUTHOR]

Based on the electroosmotic reinforcement mechanism of pulsating direct current (PDC) with a high energy efficiency ratio, the calculation method of PDC electroosmosis drainage rate was verified under different potential gradients using two forms of voltage loading, i.e., constant direct current (CDC) and PDC. The drainage weight and electric current were achieved by laboratory tests, and then the energy efficiency ratio, soil resistivity and contact resistance was calculated. The energy consumption of each test group was analyzed by considering the initial potential gradient. The obtained results show that under the same potential gradient, the difference in soil resistivity and electroosmotic drainage between PDC and CDC is not significant, but there is a significant difference in contact resistance, which leads to low current intensity and high energy efficiency ratio in the PDC test group. The expression of the electroosmotic drainage rate of the PDC is described with the coefficient μ, and then the energy efficiency ratio versus potential gradient curve is calculated, which is in good agreement with the experimental results. The reason for the lower energy consumption of PDC electroosmosis compared to CDC is described in terms of the drainage mechanism of electroosmosis.

The energy consumption of existing buildings is not only affected by their physical features but also by their business activities (e.g., operating hours, number of workers, and climate). Energy Star's energy efficiency ratio (EER) is a key energy performance indicator that has been used for more than 20 years. This method normalizes operation characteristics by calculating the estimated energy consumption of business activities using regression models and comparing it with the actual energy consumption. However, EER-based assessment is limited by the lack of information regarding the reasons for the evaluation results. This study proposes a balanced method for explaining the reasons underlying energy efficiency levels while maintaining the existing EER assessment system. The method constitutes data collection, EPI derivation, and energy performance assessment, utilizing the parameters of the change-point linear model (CPM) as an additional EPI to provide descriptive information. The results are summarized to provide a checklist guide for retrofitting, and additional energy saving potential for buildings with low and high scores can be identified by comparing the EER scores and CPM parameters. The proposed method shows that it is possible to interpret the energy efficiency assessment results by comparing CPM parameters, while maintaining the EER score. [ABSTRACT FROM AUTHOR]

The conducted experimental studies of the linear compressor concerned the cooling capacity, efficiency, and Energy Efficiency Ratio (EER). Linear compressor performance tests were carried out for the supply voltage of 190-265 V and the supply frequency in the range of 45-65 Hz, which allowed the compressor to be tested outside its typical operating range. Modulation of the performance was achieved using an inverter. The full range of performance characteristics of a linear compressor was presented. The results were compared with a reciprocating compressor for similar displacement volume, which achieved lower EER values by an average of 38% for a pressure ratio above 1.7. The power consumption of a linear compressor is on average two times lower than that of a reciprocating compressor. [ABSTRACT FROM AUTHOR]

The construction of a maritime cold chain network with islands as node is an important avenue for the economic development of the island, in which efficient refrigeration technology is essential to the development of the marine industry. Motivated by the substantial resources of tropical ocean, an absorption-compression refrigeration device is constructed and its technical feasibility is firstly demonstrated by experiment, achieving a refrigerating capacity of 6.8 kW and 10.2 kW at the evaporation temperature of −24.5 °C and −18 °C, respectively. The pressure rise by the compressor has been reduced by 185 kPa when compared to traditional vapor-compression refrigeration. The energy-saving potential of different refrigeration methods is also summarized, with the proposed refrigeration achieving the highest level of energy-efficient ratio, EER = 6.57. Especially, the proposed refrigeration can be cascaded with power generation, desalination, chilled-soil agriculture, and aquaculture to realize the gradient utilization of ocean thermal energy and hence improve the overall economy. This work opens up a new path for promoting and developing the use of ocean thermal energy for blue ocean economy in tropical oceans with bathymetry depths of 300 m or higher. [ABSTRACT FROM AUTHOR]

The control strategy is important for variable refrigerant flow (VRF) air conditioning system to realize energy saving and stable operation. In this work, the super‐heating degree (SHD) responsive control strategy was developed to dynamically adjust the respective SHD target value (ΔTe,tar) of indoor units so as to adapt to the variable cooling load. The capacity code (Ecode) is introduced into the control model to quantify the reference target value of SHD. To responsively adapt to variable cooling load, the correction target values of SHD based on discharge temperature and deviation of the outlet air temperature are introduced in the SHD model for operation protection of the compressor and the consistency of refrigerant distribution. The enthalpy difference analogy method is developed to estimate the performance of the VRF system including cooling capacity, electric power, and energy efficiency ratio (EER). The performance was tested under the conditions of different ΔTe,tar. Experimental results demonstrate that the ΔTe,tar is an important factor to determine the operation frequency, which affects cooling capacity, power, EER, and operation status of the system. The cooling capacity and electric power at the ΔTe,tar of 9°C was about 55.2% and 63.5% lower than those at the ΔTe,tar of 1°C, and the corresponding EER was improved by 22.6%. To further verify the SHD control strategy, the VRF system was tested by the responsive control model under the condition that Ecode and ΔTe,tar were constantly automatically adjusted and changed with the actual indoor ambient temperature. Experimental results demonstrate that the VRF system can achieve a good and uniform cooling effect and realize energy saving and stable operation according to the responsive super‐heating degree control. [ABSTRACT FROM AUTHOR]

This article presents the results of a three-year experiment (2018–2020) conducted at the Agricultural Experiment Station in Bałcyny (north-eastern Poland) with the aim of determining Jerusalem artichoke (JA) yields and the energy balance of biomass production in (i) a perennial cropping system (only aerial biomass was harvested each year) and (ii) an annual cropping system (both aerial biomass and tubers were harvested each year). When JA was grown as a perennial crop, the demand for energy reached 25.2 GJ ha−1 in the year of plantation establishment and 12.3–13.4 GJ ha−1 in the second and third year of production. The energy inputs associated with the annual cropping system were determined in the range of 31.4–37.1 GJ ha−1. Biomass yields were twice as high in the annual than in the perennial cropping system (20.98 vs. 10.30 Mg DM ha−1). Tuber yield accounted for 46% of the total yield. The energy output of JA biomass was 1.8 times higher in the annual than in the perennial cropping system (275.4 vs. 157.3 GJ ha−1). The average energy gain in JA cultivation ranged from 140 (perennial crop) to 241 GJ ha−1 (annual crop). The energy efficiency ratio of JA biomass production reached 7.7–13.3 in the perennial cropping system, and it was 20% lower in the annual cropping system. These results imply that when JA was grown as an annual crop, an increase in energy inputs associated with plantation establishment (tillage and planting) and the harvest and transport of tubers was not fully compensated by the energy output of tubers.

Broadly defined climate protection is a powerful incentive in the search for environmentally friendly refrigeration technologies. Adsorption chillers are considered to be one such technology; however, their main disadvantages include a low cooling capacity, a low energy efficiency ratio (EER), and cyclic operation. Thus, a great deal of effort is being put into improving adsorption-chiller performance. In this paper, the influence of the spray angle, the number of nozzles, and the water flow rate through the nozzles on adsorption-chiller performance was investigated. Adsorption-chiller performance was investigated mainly in terms of the cooling capacity (CC), the energy efficiency ratio (EER), and the specific cooling power (SCP). The results indicated that the chiller’s cooling capacity increased from about 210 W to 316 W and that the EER increased from 0.110 to 0.167 when the spray angle of the nozzles was increased from 90° to 120°. It was also reported that increasing the flow rate of water through the nozzles did not improve the average cooling capacity or the other performance parameters but resulted in more stable operation of the chiller. Additionally, using six nozzles instead of three improved the average cooling capacity and EER tenfold.

The purpose of this research is to analyze the performance of an air conditioner that uses natural refrigerant R290 both analytically and experimentally. The feasibility of R290 for R22 air conditioner is examined thoroughly. Since the alternatives used in R22 air conditioners possess high GWPs and they are controlled by the Kyoto Protocol. The Kyoto Protocol mainly indicates that the high GWP refrigerants used in refrigeration and air conditioning sectors are classified into one among the targeted greenhouse gases. Therefore, the present work focuses on ecofriendly-refrigerant R290 as a substitute to R22. In comparison to R22, R290 has no ODP and a very low GWP. An analytical study is conducted based on the actual VCR cycle. An experimental study was conducted on the R22 air conditioner with R290 at various outdoor conditions. Test results revealed that electrical energy consumption of air conditioner with R290 was 12.30% lower compared to R22 for the lower operating conditions and it was 11.40% lower compared to R22 for the higher operating conditions. Cooling capacity of R290 compared to R22 is lower in the range of 6.37–9.24% for the test conditions studied. For the operating circumstances studied, the energy efficiency ratio of R290 is higher than R22, ranging from 2.41 to 6.77%. Compressor discharge temperature of R290 is lower in the range of 8.67–15.32 °C for all the investigated conditions. When compared to R22, CO2 emissions from air conditioners operating with R290 are lower in the range from 13.10 to 14.18%. The study revealed that R290 is a viable option to replace R22 used in air conditioners in terms of performance and environmental aspects. [ABSTRACT FROM AUTHOR]

The dry scroll vacuum pump is a kind of variable capacity dry vacuum pump that is applied in chemical, pharmaceutical, semiconductor, and scientific instruments. Analyzing the thermodynamic characteristics of the scroll vacuum pump and studying the impact of operating temperature on its consistent performance are necessary for the design and application of the cooling system of the scroll vacuum pump. Based on the dynamics mesh method, the computational fluid dynamics (CFD) simulation model of a multi-stage dry scroll vacuum pump is established in this study. Under the suction pressure of 1000 Pa, the simulation calculation is carried out at different operating temperatures of fixed scrolls (25 °C, 45 °C, and 65 °C). The results show that the pumping speed, the gas compression power, and the energy efficiency ratio are significantly affected by different temperatures. The operating temperature of the pump has been reduced from 65 °C to 25 °C, the pumping speed is increased by approximately 5.97%, the gas compression power is increased by approximately 4.32%, and the energy efficiency ratio is increased by approximately 1.745%. This research provides a transient simulation method using dynamic mesh technology for the study of the dry scroll vacuum pump, and the results can provide a theoretical basis for the design and application of the cooling system of the dry scroll vacuum pump. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On a microwave radiation triaxial loading experimental system with independent intellectual property rights, seepage experiments of coal samples were condected under the action of different microwave radiation power, radiation time, and effective force, the key factors affecting the permeability of coal samples were analysed, and the actual structural coal seam infiltration was reasonably predicted. According to the heating experiments, the fitted formula of surface temperature, radiant powers and radiation time of coal samples was obtained. The main influencing factors of permeability: effective force, radiated power, and their sensitivity were analyzed. The synergistic permeation of radiation power and radiation time in the form of energy consumption ratio was draum. It is concluded that higher microwave power infiltration should be selected. Through the analysis of the influence of radiation power, radiation time, and effective force on coal sample permeability, the mechanism of microwave radiation permeation increase is clearar, which has a theoretical reference and guidance for the capacity prediction of microwave radiant thermal recovery technology.

In this paper, the optimal refrigerant mass charge amount of R417A, as a substitute for R22, was experimentally investigated in a split‐type air‐conditioner with no changes in system configuration. Experiments were conducted for both refrigerants over a range of mass charge from 500 to 850 g in a 12,000 Btuh−1 split air‐conditioner as the case study which is a conventional refrigeration system in residential sector of Iran. In order to study the effect of refrigerant mass charge on performance of refrigeration cycle, energy and exergy analysis were performed to determine cooling capacity, energy efficiency ratio (EER) and exergy efficiency. Results showed that the maximum EER for R22 and R417A are 2.48 and 2.41, and the maximum exergy efficiencies obtained for R22 and R417A are around 7.3% and 7%, respectively. Based on both EER and exergy efficiency, the optimum mass charge for R22 and R417A refrigerants are around 640 g and 650 g, respectively. In addition, it was found that under optimal charge conditions, the cooling capacity, EER and exergy efficiency of the system while working with R417A are lower than R22, just by 2.5%, 3%, and 4.5% respectively. Comparison results indicate that R417A can be considered as a suitable substitute for R22, which can almost provide the same performance without need to change the system components. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Refrigeration is the property of Journal of Refrigeration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The energy consumption of existing buildings depends on their physical features, climatic conditions, and business activities, such as operating hours and occupancy characteristics. It is necessary to perform a fair assessment of building energy performance considering the business activities. It has become especially necessary to collect and manage information on business activities in hospitals since hospitals operate continuously throughout the year, treating patients and using various medical equipment. This study aimed to develop a benchmark that considers business activities and to perform building energy performance assessments in hospitals using the developed benchmark. Initially, the necessary data from hospitals for assessing energy performance and developing an energy benchmark were identified. Then, survey items regarding the business activities and energy consumption of buildings were designed, and a survey was conducted at 48 general hospitals. Secondly, multiple linear regression was used to identify and normalize the major business activities affecting energy use and to develop a benchmark for energy performance assessment. Thereafter, the Energy Efficiency Ratio (EER), the result of comparing the actual energy consumption with the benchmark, was used as an index for the energy performance assessment. Thirdly, additional general hospitals were surveyed to validate the benchmark. The EER of the additional surveyed hospitals was calculated with the developed benchmark. The Energy Use Intensity (EUI) and EER of buildings were reviewed, and analysis was performed to identify why some buildings had a similar EUI but a different EER. Finally, a method to improve the benchmark is presented, and the improved benchmark model is compared with the existing model. [ABSTRACT FROM AUTHOR]

• Hydrate decomposition was enhanced by circulating warm water from the deep gas layer. • Increasing the flow rate of the circulating water improved the production efficiency. • A cycling regulation of the hybrid water flow rate could enhance the EER by 16.23 %. Utilizing the geothermal energy from the deep gas layer to enhance the hydrate decomposition is a potential clean production approach, avoiding the vast costs and severe pollution in the traditional heat injection scheme. In this work, a novel method was proposed to promote hydrate decomposition by employing circulating water to transport heat from the deep gas layer. Results showed that increasing the water flow rate from 9.82 mL/min to 39.28 mL/min could significantly improve the production efficiency by 27.27 %. Yet, the energy efficiency ratio (EER) slightly decreased by 3.31 % due to the increased power consumption of the water pump. A hybrid water flow rate was thus used with a lower rate in the later production stage when the heat absorption of hydrate decomposition was declining accordingly. This was found to successively improve the EER by 2.68 % while maintaining comparable production efficiency; a further cycling regulation (intermittent circulating) of the hybrid water flow rate could significantly enhance the EER by 16.23 %. The results could guide the efficient utilization of natural geothermal energy to facilitate the large-scale gas production from the natural gas hydrates when heat supply from the surrounding sediments was limited. [ABSTRACT FROM AUTHOR]

The energy consumption of existing buildings is not only affected by their physical features but also by their business activities (e.g., operating hours, number of workers, and climate). Energy Star’s energy efficiency ratio (EER) is a key energy performance indicator that has been used for more than 20 years. This method normalizes operation characteristics by calculating the estimated energy consumption of business activities using regression models and comparing it with the actual energy consumption. However, EER-based assessment is limited by the lack of information regarding the reasons for the evaluation results. This study proposes a balanced method for explaining the reasons underlying energy efficiency levels while maintaining the existing EER assessment system. The method constitutes data collection, EPI derivation, and energy performance assessment, utilizing the parameters of the change-point linear model (CPM) as an additional EPI to provide descriptive information. The results are summarized to provide a checklist guide for retrofitting, and additional energy saving potential for buildings with low and high scores can be identified by comparing the EER scores and CPM parameters. The proposed method shows that it is possible to interpret the energy efficiency assessment results by comparing CPM parameters, while maintaining the EER score.

M-cycle (Maisotsenko cycle) based indirect evaporative cooling system can significantly enhance the natural ecosystem. The operating cost of dewpoint indirect evaporative cooler (Dewpoint-IEC) is low for space air cooling systems. Dewpoint-IEC is inexpensive, energy efficient, and ecological friendly. This study illustrates the experimental evaluation of Dewpoint-IEC working with varying operating conditions. The system designed for up to 1 Ton cooling capacity of the system which has coefficient of performance and energy efficiency ratio up to 6 and 20. The experimentation of Dewpoint-IEC is investigated in terms of the relative humidity and ambient temperature. The results indicate that the effectiveness of the Dewpoint-IEC system is increased with decrease the relative humidity and increase the ambient air temperature. The highest experimental values of wet bulb and dewpoint effectiveness of the system is 1.11 and 0.76. The maximum resulting values of EER, COP, and cooling capacity is 19, 6.1, and 3.3 kW, respectively. Based on experimental results, the system is a feasible option in hot summer days. Moreover, the power consumption of the DewpointIEC is 70 W which can be achieved by combining the system with solar panels. So, current research also shows that Dewpoint-IEC integrated with solar panel recommends off-grid solution as well. Keywords: Maisotsenko-cycle; Indirect evaporative cooler; [ABSTRACT FROM AUTHOR]

A method of using condensate water to reduce the airflow temperature around the air conditioner condenser and improve the performance of air conditioner is presented in this study. The structure of traditional split air conditioner is adjusted by changing the installation direction of fan and adding disk-type atomization cooling element (ACE) in the outdoor unit. The performance of the air conditioner under four modes is tested in different environment temperatures. Four modes were named, i.e. the original unit without ACE, original unit with ACE, blowing mode without condensate water and blowing mode with condensate water. The blowing mode with condensate water is used to pre-cool the incoming airflow, and the maximum temperature reduction at the air outlet surface of the condenser is up to 2.2 °C in 35 °C. With the environment temperature increasing, the refrigerating capacity of four modes decreased, and the power consumption increased, leading to the decrease of EER. However, owing to the cooling effect of condensate water, the performance of blowing mode with condensate water was greatly improved compared with the original unit without ACE. The variation rates of refrigerating capacity, power consumption and EER at environment temperature of 43 °C were 8.1%, -9.5% and 20%, respectively. The unit with condensate water could greatly improve the performance of air conditioning in high environment temperatures.

The dry scroll vacuum pump is a kind of variable capacity dry vacuum pump that is applied in chemical, pharmaceutical, semiconductor, and scientific instruments. Analyzing the thermodynamic characteristics of the scroll vacuum pump and studying the impact of operating temperature on its consistent performance are necessary for the design and application of the cooling system of the scroll vacuum pump. Based on the dynamics mesh method, the computational fluid dynamics (CFD) simulation model of a multi-stage dry scroll vacuum pump is established in this study. Under the suction pressure of 1000 Pa, the simulation calculation is carried out at different operating temperatures of fixed scrolls (25 °C, 45 °C, and 65 °C). The results show that the pumping speed, the gas compression power, and the energy efficiency ratio are significantly affected by different temperatures. The operating temperature of the pump has been reduced from 65 °C to 25 °C, the pumping speed is increased by approximately 5.97%, the gas compression power is increased by approximately 4.32%, and the energy efficiency ratio is increased by approximately 1.745%. This research provides a transient simulation method using dynamic mesh technology for the study of the dry scroll vacuum pump, and the results can provide a theoretical basis for the design and application of the cooling system of the dry scroll vacuum pump.

This paper presents a new type of split natural cooling system that maximizes the use of natural cold energy to significantly reduce the power consumption of the air conditioning system in data centers. A split natural cooling system module, which consisted of indoor and outdoor heat exchanger based on micro heat pipe arrays connected by liquid circulation system, was selected for experimental research. The heat transfer process and flow characteristics were analyzed under different outdoor environment temperatures, air and water flow rates, and different ratios of heat transfer components (N) of indoor and outdoor heat exchangers. To improve the utilization of natural cold energy, two kinds of heat dissipation conditions, namely room and heat channel-based, were proposed. The indoor temperature of two conditions at 28 °C and 38 °C were simulated in the laboratory at constant temperature-humidity, respectively. Results indicated that the air flow rate had a greater influence on the heat transfer performance than the water flow rate. The pressure drop of the air and water sides was at a lower level, and the fitting curve of the pressure drop was obtained to provide a reference for the heat exchanger design and equipment selection. When the ratio of heat transfer components (N) of the indoor and outdoor heat exchanger was approximately 0.75, the split natural cooling system showed optimal comprehensive performance. Under heat channel-based conditions, the maximum heat transfer rate reached 12.4 kW, and the maximum energy efficiency ratio was 17.15; the maximum heat transfer rate and the maximum energy efficiency ratio increased by 42.5% and 22.64% compared with the room-based condition, respectively. The fitting curve of the energy efficiency ratio was calculated under different outdoor temperatures at two heat dissipation conditions. [ABSTRACT FROM AUTHOR]

A two-year field experiment was conducted in Poland to determine energy efficiency (EE) in the production of winter oilseed rape (WOR) in different fertilization: (i) zero-fertilization; (ii) 158 kg N ha−1, 45 kg P ha−1 and 145 kg K ha−1 as mineral fertilizer (NPK); (iii) 1.0 Mg ha−1 meat and bone meal (MBM), 79 kg N ha−1 and 145 kg K ha−1 as mineral fertilizer; (iv) 1.5 Mg ha−1 MBM, 40 kg N ha−1 and 145 kg K ha−1 as mineral fertilizer; and (v) 2.0 Mg ha−1 MBM and 145 kg K ha−1 as mineral fertilizer. The replacement of NPK with MBM decreased energy inputs in WOR production by 20−55%. The NPK had a greater (16–21%) effect on seed yield formation than MBM. The replacement of NPK with MBM decreased the energy output of seeds (14–21%) and total biomass (12–20). The replacement of NPK with MBM decreased (6–13%) the energy gain from seed production. The application of MBM improved the EE ratio in the production of seeds (10–81%) and total biomass (11–85%) relative to NPK. The EE ratio of WOR production increased with a rise in MBM doses. [ABSTRACT FROM AUTHOR]

Air-cooled chillers are extensively employed to meet cooling demand in commercial and tertiary sectors. To enhance their performance during part-load operation, variable-speed drives have been integrated into compressors and condenser fans. In existing systems, condenser fans are either operated at a fixed speed or modulated to maintain a predetermined condensing pressure or temperature difference between the refrigerant and outdoor air. In the search for increased efficiency, it is worth investigating innovative control strategies aimed at minimizing energy consumption. A preliminary mapping of chiller performance at different fan speeds, loads, and operating conditions is required to achieve this goal. In this respect, this paper investigates the operation of air-cooled chillers equipped with variable-speed condenser fans, both in the case of constant- and variable-speed compressors. An ad hoc matrix test is adopted to cover appropriate ranges conditions, in terms of load and outdoor air temperatures. Performance maps are developed for a 50-kW c chiller using a 1-D simulator. As the main findings, it may be stated that (i) in the case of the variable-speed chiller, the energy efficiency ratio increases almost linearly with fan speed, resulting in an 8.8% increase when increasing the speed from the nominal to the maximum; (ii) in the case of constant-speed chillers, the system exhibits a different behavior with the cooling capacity and the energy efficiency ratio increasing with the fan speed between 380 and 980 rpm and then decreasing (slightly or sharply, at full and part load respectively) with fan speed between 980 and 1280 rpm, and a percentage increase of EER in the range 7.8–45% is observed. Also, the sensitivity of such results to the system design is investigated, analyzing a chiller equipped with a larger condenser that resulted in achieving minimum energy consumption at an optimal 980 rpm fan speed. Finally, for a constant-speed chiller serving an office building in the Mediterranean, the proposed fan control strategy could yield an electricity saving of up to 12.1% compared to the base case, confirming the potential for energy savings through optimized and system-tailored management of condenser fan speed. • The effect of variable-speed fans on the performance of air-cooled chillers is investigated. • Maps are developed for chillers with both variable-speed and constant-speed compressors. • Fan speed significantly influences the cooling capacity of constant-speed chillers. • In variable-speed chillers, it is advisable to always run the condenser fan at high speed. • The enhanced fan strategy enables 12.1% energy savings for a chiller in an office building. [ABSTRACT FROM AUTHOR]

In order to ensure the safety and stability of the cooling system during the operation of the battery thermal management system combined with composite phase change material cooling and liquid cooling, it is usually necessary to continuously pump cooling water. It inevitably caused that the latent heat of composite phase change material could not be fully released and extra pump power was consumed. In the study, five different energy saving strategies were proposed and the energy efficiency ratio was defined to evaluate their cooling effects and energy saving. The effect of energy saving strategies on energy consumption of liquid cooling and latent heat utilization of composite phase change material was analyzed. The results show that III and V can meet their cooling requirements and have a high energy efficiency ratio. The screw pitch and cooling water flow rate in these two modes were investigated. The results show that the increase in screw pitch reduces the heat transfer efficiency, resulting in an increase in T max and Δ T max , and Δ T max exceeding the maximum range. Diminishing the cooling water flow will precipitate a rise in battery temperature, enabling the CPCM to operate at its maximum capacity and consequently decreasing Δ T max. As a cooling water flow of 20 ml/min in III and V all can satisfy the cooling requirements. Additionally, the III was also competent when the cooling water temperature was raised from 25 °C to 35 °C. [ABSTRACT FROM AUTHOR]

In residential air conditioning systems, outdoor units are often installed in the recesses of building facades and shaded by louvres; however, different unit installation positions and louvre blade angles affect the thermal environment around the outdoor unit and the energy efficiency ratio (EER) of the air conditioner. In this study, the effects of the outdoor unit installation position and louvre blade angle on the EER when a single outdoor unit was installed in a recess were investigated by experiments on a 1.5 hp air conditioner (rated power of the air conditioner is 3.5 kW), and the influence of the spacing and angle between two outdoor units on the air conditioner EER when two outdoor units were installed in the same recess was explored. The results of the research indicate that when a single outdoor unit is installed in the recess, the EER increases with an increase in the distance between the inlet of the outdoor unit and the wall. To meet the three-level standard of air conditioner EERs, the distance between the inlet and wall needs to be greater than 300 mm. The EER first increased and then decreased slowly with the increase in the distance between the outdoor unit outlet and louvre; thus, the distance between the outlet and louvre should not be less than 300 mm. The EER first increased and then decreased with the increase in the blade angle, and thus, the blade angle should not be greater than 20°. When two outdoor units are installed in the same recess, each installation mode, "horizontal installation" (same height and collinear), "perpendicular installation" (same height and perpendicular), "angle installation" (same height and obtuse angle), and "up and down parallel installation" (different heights and parallel), has an optimum installation distance and angle. [ABSTRACT FROM AUTHOR]

In order to explore the energy efficiency of geothermal energy application under karst geological conditions in hot-summer and cold?winter zone? the system energy efficiency ratio and unit energy efficiency ratio of ground source heat pump system were predic? ted based on the optimized back propagation neural network model by genetic algorithm (GA?BP) under the condition that system load rate was below 30% in summer. It was verified that the GA?BP model has higher prediction accuracy by the prediction error evaluation indicators. The relationship between short-term test and medium and long-term evaluation of energy efficiency ratio was studied by the prediction model. The results show that the relative error of the predicted value and the calculated value is ± 5%. The predicted values of system energy efficiency ratio COPsys and unit energy efficiency ratio COP are predicted by the GA-BP neural network model. All prediction error evaluation indicators are smaller than back propagation neural network (BPNN) prediction model. This shows that GA-BP model can be used to predict energy efficiency of ground source heat pump system under karst geological conditions. The optimal time for conducting short-term monitoring is 14:00—16:00 of the day or 13 days in total in July and August and meet the unit load rate of 60% ~ 70% based on the prediction model. The short-term predicted values of COPsys and COP for are applied to the medium and long-term efficiency ratio evaluation. The relative error of the evaluated energy efficiency ratio is within the allowable range. [ABSTRACT FROM AUTHOR]

Summary: The flow field of the proton exchange membrane fuel cell (PEMFC) controls mass and water transfer; it significantly impacts the fuel cell's performance. It is critical to innovate the flow field design for optimizing the performance. This paper proposes a new‐designed flow field (NDFF) patterned with the built‐in blockage and trap‐shape rib association. The novel design was analyzed numerically and experimentally. A three‐dimensional isothermal numerical model was first established based on COMSOL software. This model demonstrated that the NDFF transformed the traditional diffusion mass transfer into the optimized diffusion and convection mass transfer combination. Compared with the conventional straight flow field, the effective mass transfer coefficient was considerably improved. Moreover, the new‐designed structures enforced cyclical variation of local velocity and pressure, forming forced‐convection, which was beneficial for water management. At 0.45A·cm−2, the steady‐state voltage and the initial dynamic response voltage were increased by 0.08 V and 0.16 V; power density was increased by 20.1%. The experimental results were collected to validate the enhanced performance of PEMFC with the NDFF. Energy efficiency ratio (EER) was proposed as an evaluation criterion; EER results suggested NDFF can improve the net output power. Highlights: A new flow field patterned with built‐in blockage and trap shape rib associationEnergy efficiency ratio, effective mass transfer coefficient used for evaluationSteady‐state and dynamic performances are greatly improved at an increased Energy efficiency ratio [ABSTRACT FROM AUTHOR]

The present research is about increasing the energy efficiency ratio (EER) in current direct evaporative coolers (DEC) in Iran. Increasing the cooling load and reducing the electrical energy consumption simultaneously (increasing the energy efficiency ratio (EER)) in DEC are the main goals of manufacturers and consumers of this device. When the circulation water pump runs continuously (static state), the circulation water rate is about 1.89 to 2.90 times of the amounts recommended in the reasonable standards. In order to adjust the circulation water rate to the recommended amount by standards, the present study has utilized repetitive cyclic scheduling programs to reduce the circulation rate to the optimal amount, (by turning the circulation pump on and off by dynamic pattern operation). In other words, the circulation pump stays on only for a certain period of a working cycle, and then the pump stays off for the rest of it. The cooling load and EER were measured based on ASHRAE 133 (2015). The results indicated that the cooling load in the dynamic state increased by 5.03 and 6.18 percent compared to the static state at low and high fan speeds, respectively. Moreover, in comparison with the static state, the amount of electrical energy consumed (kW-hr) in the dynamic state decreased by 8.8 and 4.2 percent at low and high fan speeds, respectively. Finally, the coefficient of performance (COP or EER) of the DEC in the dynamic state is increased by 15.16 and 10.78 in comparison with the static state at low and high fan speeds, respectively. [ABSTRACT FROM AUTHOR]

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A comparative analysis of the Coefficient of Performance (COP) and the Energy Efficiency Ratio (EER), based on the technical data of 430 different models of air-to-water heat pumps (AWHPs) as well ground-source heat pumps (GSHPs), at certain conditions of ambient air, ground source and water outlet from the heat pump (HP) temperatures, is performed. The results, presented in graphical and tabular form, give the COP and EER values against the HPs nominal capacity and the correlation between COP and EER with the temperature rise ΔΤ along the HP. By averaging the performance values of all AWHPs or GSHPs models, equations of polynomial regression that give the relationship between average COP or EER and ΔΤ values were also calculated. It is shown that inverter-driven HPs generally have higher COP and EER as compared to the fix-capacity HPs, for the same heating or cooling range. Also, performance is highly depended on ΔΤ.

It is known that significant saving of nitrogen fertilizers are due to perennial legume-cereal grasses use in crop rotations. From 2013 to 2018in the Mari El Republic six-field grass-grain fodder crop rotations were compared on sod-podzolic soils with a very high level of phosphorus and potassium. In the third rotation their productivity and bioenergetic efficiency, changes in several important soil fertility indicators, and crud protein content in the produced fodder were evaluated. The main difference between the crop rotations was based on the duration of the clover-alfalfa-timothy grass mixture (CAG) use: from one year to three years. In given experiment there was also studied the effect of mineral nitrogen (variants N0, N60) against Р60К60 background on the yield of crop rotations. During six years, there was no significant soil acidification in the variants. Each additional year of clover-alfalfa-timothy grass mixture use raised the energy efficiency ratio of crop rotations by 24-47 % (from 1.13-1.24 by one-year use to 2.08-2.25 by three years of use). Three-year CAG use as compared with one- and two-years has given to the crop rotation significant advantages in energy efficiency (up to two times) and productivity (approximately 40-80 %) of cultivated crops. After refusing to apply nitrogen fertilizations in such crop rotation, average crop productivity, soil humus and nitrogen content in the soil were better preserved. The average crude protein content in dry matter of the obtained fodder increased from 12.7 % to 14.6 % when prolonging theca use up to two years. The average energy value of the yield per rotation was recorded low (8.4-8.7 MJ/kg) and did not depend on the studied factors.

The primary aim of this study was to assay the influence of pellet and mash diets supplemented with different levels of mesquite fruit on performance, energy and protein efficiency ratio, carcass characteristics, and intestinal morphology of broiler chickens. In this study, a total of 560 one-day-old (mixed sex) Ross 308 were distributed in a completely randomized design with 7 treatments, 4 replicates, and 20 chicks per replicate. Seven iso-caloric and iso-nitrogenous diets including a control diet (mash form without mesquite fruit), and pelleted and mash diets, consisting of three levels of mesquite fruit (3, 6, and 9%) were adjusted. The results exhibited that mesquite fruit contained a high percentage of dietary fiber. The results also showed that pelleted and mash diets containing different levels of mesquite caused a significant difference in feed intake, body weight gain, and feed conversion ratio in starter and grower periods. At the finisher period, there was a significant difference between the experimental treatments in terms of feed intake and body weight gain, but there was no significant difference in feed conversion ratio. Experimental treatments also caused a significant difference in energy and protein efficiency ratio in the starter and grower periods. Dietary treatments also exhibited a significant difference in the relative weight of breast and intestine, but no effect was found on carcass yield and relative weight of other internal organs. The findings revealed that pelleted and mash diets containing different levels of mesquite fruit did not show significant differences in morphological traits of the intestine. Taken together, our results suggested that, the use of mesquite fruit in pelleted diets can have positive effects on the performance of broilers.

The energy consumption of existing buildings depends on their physical features, climatic conditions, and business activities, such as operating hours and occupancy characteristics. It is necessary to perform a fair assessment of building energy performance considering the business activities. It has become especially necessary to collect and manage information on business activities in hospitals since hospitals operate continuously throughout the year, treating patients and using various medical equipment. This study aimed to develop a benchmark that considers business activities and to perform building energy performance assessments in hospitals using the developed benchmark. Initially, the necessary data from hospitals for assessing energy performance and developing an energy benchmark were identified. Then, survey items regarding the business activities and energy consumption of buildings were designed, and a survey was conducted at 48 general hospitals. Secondly, multiple linear regression was used to identify and normalize the major business activities affecting energy use and to develop a benchmark for energy performance assessment. Thereafter, the Energy Efficiency Ratio (EER), the result of comparing the actual energy consumption with the benchmark, was used as an index for the energy performance assessment. Thirdly, additional general hospitals were surveyed to validate the benchmark. The EER of the additional surveyed hospitals was calculated with the developed benchmark. The Energy Use Intensity (EUI) and EER of buildings were reviewed, and analysis was performed to identify why some buildings had a similar EUI but a different EER. Finally, a method to improve the benchmark is presented, and the improved benchmark model is compared with the existing model.

• A novel radiant-convective cooling system is proposed. • The thermal comfort, energy and economic performance are experimentally studied. • The proposed system has better indoor thermal comfort than split air-conditioners. • The proposed system has higher energy efficiency ratio than split air-conditioners. Split air-conditioners have limitations in terms of energy efficiency and local comfortability. Radiant cooling systems (RCSs) cannot be used in most residential buildings, due to its lack of space for a central plant room to achieve secondary heat exchange. To overcome these defects, a novel radiant-convective cooling system with the refrigerant-cooling radiant terminal (RCRT) was proposed, which took the advantages of both split air-conditioners and RCSs. Experiments were conducted in a climate chamber to investigate the thermal comfort performance, energy efficiency ratio and economic performance of the proposed system, in comparison with split air-conditioners. The results indicated that the RCRT cooling system could improve the indoor set temperature from 26°C to 28°C, under the same indoor thermal comfort as split air-conditioners. Additionally, the proposed system had higher energy efficiency ratio than split air-conditioners, and the energy saving potential of this system was 8.4%. The initial cost of the RCRT cooling system was higher than split air-conditioners, however, its life cycle cost was lower. The payback period of using the proposed system to replace split air-conditioners was 2.4 years, indicating that adopting the RCRT cooling system was more economical. [ABSTRACT FROM AUTHOR]

• The recommended refrigerant charge is the same for the three refrigerants. • R513A reduces the total electric energy input per hour of operation in 3.9% for 32°C. • Isobaric assumption in the evaporator under-predicts the cooling duty up to 18.7%. • The experimental EER does not give a clear guide to the refrigerant charge. In this study, an experimental determination of the refrigerant charge and the operating conditions in a vertical display refrigerator using R134a, R513A, and R1234yf is presented. The three refrigerants' energy inputs under ambient temperatures of 24, 32, and 40°C are compared. The refrigerator is instrumented with a mass flow meter, thermocouples, and pressure transducers. The evaluations are carried out inside a room with controlled temperature and air recirculation. For each analysis, the refrigerator is operated for a period long enough until differences among operation on/off cycles are negligible. Batch loads of 15 g are used for determining an adequate refrigerant charge. The results show a recommended charge of 175g for the three refrigerants and the range of temperatures. The electric energy consumption increase on average 20 kJ per hour of operation for every degree the ambient temperature increases. Compared with R134a, the R513A results in lower energy input in 3.8, 3.9, and 0.3% for 24 and 32 and 40°C, respectively. The experimental determination of EER values does not give accurate guidance for the adequate refrigerant charge. The assumption of isobaric heat exchange results in a maximum deviation of the actual cooling duty of 13, 18.7, and 16.6% for R134a, R1234yf, and R513A, respectively. [ABSTRACT FROM AUTHOR]

An experiment has been carried out for examining the performance of an air conditioning unit under constant outdoor wet-bulb temperature and varied dry-bulb temperature. During the experiment, the wet-bulb temperature of the compartment for outdoor unit was maintained at 22 °C and the dry-bulb temperature was varied from 24°C to 36°C. The increase of outdoor air temperature results in the increase of supply air temperature, discharge temperature, suction temperature, and liquid line temperature. These cause the degradation of the air conditioner performance. An increase of power consumption by 1.4% and decrease of cooling capacity by 0.8% were observed for each 1°C increase of outdoor air temperature. As a result, the energy efficiency ratio drops by 2% for each 1°C increase of outdoor air temperature. [ABSTRACT FROM AUTHOR]

This research studied the direct evaporative cooling technique for generating cool air in hot–dry and hot–humid climates. For direct evaporative cooling, three parameters affected the air temperature: feedwater temperature, wet-bulb temperature, and mass ratio of feedwater to circulating air were investigated. When the feedwater temperature was lower than the wet-bulb temperature, in a hot-humid climate, an increase in the mass ratio of feedwater to the circulating air decreased the outlet air temperature. Conversely, if the feedwater temperature was higher than the wet-bulb temperature, in a hot-dry climate, a decrease in the mass ratio was needed to reduce the air temperature. The cooled air obtained could be used for condenser cooling of air-conditioner for performance enhancement. According to a 1 TR air conditioner simulation, lower feedwater temperature resulted in higher energy efficiency ratio. High mass ratio, thus, was recommended in the hot-humid climate area whereas less mass ratio was preferable for the hot-dry climate area. The energy efficiency ratios of the unit with direct evaporative cooling for hot–dry and hot–humid climates ranged from 3.40 to 4.22 and 3.30 to 3.94, respectively, compared to 3.01 for the normal unit. The payback period for the unit with direct evaporative cooling in case of Chiang Mai (hot-humid climate) was around 2.87 year.

The overwhelming evidence of global warming caused by human activities documents both contemporary impacts on human life but also extraordinary future risks are also assisted with it. Accretion of global temperatures engenders the extensive use of air conditioning devices to make the surrounding livable in the summer season. Energy consumption for air conditioning is also palpable by the evidence that this industry is the 2nd largest power-consuming sector in the consumer field. High temperatures also affect the performance of the air conditioning system by decreasing their energy efficiency ratio (EER) and cooling capacity (QC). Modifications are made in such a way to lower down the temperature of the surrounding by the use of a honeycomb wet pad which uses evaporative cooling with condensate of the indoor side. Experiments were made to observe the difference in performance efficiency, with modification and sans modification, by operating separately at 40–50 °C temperatures. Results were evident that condensate assisted evaporative cooling shows improvement in cooling capacity by 19% and a reduction in power consumption (P) by 13% as compare to the conventional system. A huge increase in the energy efficiency ratio of 36% was observed with the use of the modified system. The things used for the modification are cheaper and easily available in the market. [ABSTRACT FROM AUTHOR]

• A prediction model of building energy consumption is designed, which combines Gaussian mixture clustering and LGBM. • The specific normalized adaptive loss function is designed to determine the optimal parameters of LGBM model. • A novel predict-center energy efficiency evaluation criterion EE R PC is proposed, the cumulative distribution pattern is analyzed. • The comprehensive energy benchmark evaluation framework, which is based on the above prediction model and EE R PC , is proposed. With the rapid expanding of urban economy and population, how to reduce the energy consumption and improve energy efficiency of public buildings has become a key issue for energy conservation and urban development. However, due to the diversity of building usage condition, energy consumption data often has problems with nonlinearity, outliers, and diversity, which greatly reduce the accuracy of energy consumption prediction and energy conservation assessment. To overcome the above drawbacks, a regression prediction model of building energy consumption is designed, which cluster the same type of data characteristics to form a subset of equipment through Gaussian mixture clustering, and design the specific normalized adaptive loss function to determine the optimal control parameters of regression model. Furthermore, a novel predict-center energy efficiency evaluation criterion is proposed, and the cumulative distribution pattern is further statistically analyzed. Finally, the energy benchmark evaluation framework is proposed to determine the energy efficiency evaluation grade. Through comparative experimental analysis, it can be seen that the proposed prediction model can adapt to different types of building data, and have better prediction accuracy and convergence speed. The consistency and robustness of the benchmark evaluation framework and method are optimal. [ABSTRACT FROM AUTHOR]

The air source heat pump (ASHP) is operated in a low temperature and high humidity working environment. There is always a lot of frost forming on the outdoor heat exchanger, which hinders the heat transfer rate of the heat exchange surface, leading to the decrease of performance of the ASHP system. This paper presents a new type of frost-free evaporator for ASHP system. The heat transfer zone of the evaporator is composed of three parts: non-packing zone, plain finned-tube falling film zone and horizontal smooth tube bundle falling film zone. The experimental system of the frost-free evaporator is established, and the reliability of the experimental data is verified. The effects of refrigerant flow rate, inlet air temperature, fan frequency and solution spray mode on energy efficiency ratio, heat transfer expansion coefficient, air side pressure drop and exergy loss of the evaporator are studied. The performance of the evaporator is evaluated. The results show that with the increase of inlet air flow and temperature, the energy efficiency ratio of frost-free evaporator increases by about 8%–12%, and the air side pressure drop also increases. As the inlet air temperature increases from −10 to 15 °C, the heat transfer expansion coefficient of evaporator decreases by about 3%–6%, indicating that the increase of inlet air temperature will lead to an increase of sensible heat transfer ratio and a decrease of latent heat transfer ratio. The results also show that compared with no spray mode and continuous spray mode, the intermittent spray mode is more recommended as a feasible operation scheme to realize the continuous, efficient and stable operation of the new evaporator. • A performance test system with the frost-free evaporator is designed and built. • The factors affecting the performance of evaporator are analyzed and evaluated. • The reliability of the built system can meet the design requirements. • The energy efficiency ratio and exergy loss of the new evaporator are analyzed. • Intermittent spray is a feasible mode for efficient operation of the evaporator. [ABSTRACT FROM AUTHOR]