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Abstract Background Reducing energy consumption and greenhouse gas emissions is a crucial issue in the cassava starch processing industry. In this study, the integrated system combining livestock, cassava cultivation and cassava production in the same area leads to both a zero emission goal and economic efficiency, a typical example of an effective agro-industrial symbiosis. A heat exchange/recovery system was applied including the economizer, heat exchanger tank, biogas tank, and boiler. The economizer attached to the boiler’s chimney transfers heat from exhaust gases for pre-heating feed water entering the boiler. The biogas tank recovers energy from the wastewater of starch production and livestock, and the generated biogas was used as fuel for the boiler. Results The energy and exergy efficiency, energy losses, and exergy destruction for the heat recovery system were analyzed. The specific energy consumption was used to evaluate the overall energy efficiency for a cassava starch factory with a capacity of 20 tons/day. The results show that there is a high potential to recycle waste into energy in the cassava starch industry. The total energy saving and reduced greenhouse gas emissions per year of the cassava starch factory were 0.054%/year and 123,564 kgCO2/per year, respectively. Conclusions Cassava starch factories can save energy and reduce emissions when applying a heat recovery system in the integrated agro-industrial system. Excess heat from the production was used for evaporating (removal of) NH3 in wastewater flow from the biogas tank, and for heating the biogas system to enhance the efficiency of methane production. A biochar filter was attached to the economizer for adsorption of released ammonium, and the biochar after adsorption was combined with sludge from the biogas tank to produce a solid biofertilizer.

Background: Reducing energy consumption and greenhouse gas emissions is a crucial issue in the cassava starch processing industry. In this study, the integrated system combining livestock, cassava cultivation and cassava production in the same area leads to both a zero emission goal and economic efficiency, a typical example of an effective agro-industrial symbiosis. A heat exchange/recovery system was applied including the economizer, heat exchanger tank, biogas tank, and boiler. The economizer attached to the boiler's chimney transfers heat from exhaust gases for pre-heating feed water entering the boiler. The biogas tank recovers energy from the wastewater of starch production and livestock, and the generated biogas was used as fuel for the boiler. Results: The energy and exergy efficiency, energy losses, and exergy destruction for the heat recovery system were analyzed. The specific energy consumption was used to evaluate the overall energy efficiency for a cassava starch factory with a capacity of 20 tons/day. The results show that there is a high potential to recycle waste into energy in the cassava starch industry. The total energy saving and reduced greenhouse gas emissions per year of the cassava starch factory were 0.054%/year and 123,564 kgCO2/per year, respectively. Conclusions: Cassava starch factories can save energy and reduce emissions when applying a heat recovery system in the integrated agro-industrial system. Excess heat from the production was used for evaporating (removal of) NH3 in wastewater flow from the biogas tank, and for heating the biogas system to enhance the efficiency of methane production. A biochar filter was attached to the economizer for adsorption of released ammonium, and the biochar after adsorption was combined with sludge from the biogas tank to produce a solid biofertilizer. [ABSTRACT FROM AUTHOR]

The article presents a mathematical model of a mobile compressor station with a heat recovery system based on a refrigeration machine. The study outlines the heat recovery system scheme, based on which the mathematical model is developed. The model includes known thermodynamic relations for the heat load on heat exchangers, power consumed by the compressor, and the coefficient of performance of the refrigeration machine. The presented model allows for determining the efficiency of the system and conducting calculations of the equipment and units comprising it.

Variable refrigerant volume (VRV) systems operate on the principle of a cooling machine. They extract heat from one side and return it on the other, enabling them to function as a source of heat for both heating and hot water preparation, as well as a source of cold for cooling within a single building. These systems efficiently remove unnecessary excess heat outside and only introduce the required amount of heat from the outside into the building. With an appropriate configuration and setting, a VRV system can transfer heat in both directions within one system, eliminating the requirement for waste heat to be removed without use in the building. Instead, it is transferred to the desired locations where it is needed. This principle necessitates the adjustment of not only the refrigerant temperature but also its flow rate. Consequently, the VRV system can fulfil tasks that are otherwise handled by several individual systems in a building. A heat recovery VRV system was installed in a small retail store to extract waste heat generated by baking ovens during the baking process. This report provides a brief summary of electricity and energy consumption measurements taken during the summer period for cooling purposes. Sequential logic is observed and coherence is ensured, with active voice predominating for clearer and more direct communication. The parameters of interest include cooling setpoints, cooling outside of working hours, and capacity assessment. [ABSTRACT FROM AUTHOR]

Experiments were conducted in this study to examine the thermal performance of a thermosyphon, made from Inconel alloy 625, could recover waste heat from automobile exhaust using a limited amount of fluid. The thermosyphon has an outer diameter of 27 mm, a thickness of 2.6 mm, and an overall length of 483 mm. The study involved directing exhaust gas onto the evaporator. This length includes a 180-mm evaporator, a 70-mm adiabatic section, a 223-mm condenser, and a 97-mm finned exchanger. The study examined the thermal performance of the thermosyphon under exhaust flow rates ranging from 0-10 g/sec and temperatures varying from 300°C- 900°C. The influence of three parameters-inclination angle (5°-45°), water mass (2-5.3 g), and the quantity of non-condensable gas Argon (0-0.6 g)-was investigated to assess their impacts on the thermosyphon’s thermal efficiency. The experimental findings revealed that with 3 g of water and 0.0564 g of argon in the thermosyphon, the condenser reached its highest temperature at around 200°C. The ideal fuel loading rate for the thermosyphon falls between 0.2 and 0.7 g/s. Moreover, as inclination angles rise, outer wall temperatures of the thermosyphon increase. This is attributed to the explicit expansion of the effective heating area within the evaporation section, coupled with an amplified gravitational component of the water flux. Additionally, an upsurge in the quantity of non-condensable gas (NCG) can mitigate temperature gradients on the outer wall, resulting in a decline in the thermosyphon’s performance. The insulation applied to the adiabatic section demonstrated efficacy in augmenting temperature gradients on the outer wall, thereby improving the overall performance of the thermosyphon. As the water charge within the thermosyphon increases, there is a corresponding rise in heat transfer rates both from the exhaust to the thermosyphon and from the thermosyphon to the fuel. [ABSTRACT FROM AUTHOR]

Evaluates energy resources in the production of bakery products on a moving platform of a mini-bakery, with the possibility of recuperating heat flows based on their redistribution with the creation of local heating zones. The final acceptable conditions were established and a heat and mass transfer model was presented for the possible control of the energy potential of flue gas emissions and the temperature of water at the outlet of the heat exchanger in constant time.

Climate change is becoming a pressing global concern, and the search for new energy and energy recovery technologies is becoming a worldwide research imperative. The broad adaptability of the Stirling engine to a wide variety of heat sources makes it a promising technology for industrial waste heat recovery and solar thermal generation. The operation of the Stirling engine involves a multi-physical coupled process of heat transfer and mechanics as well as non-linear losses due to mechanical friction and gas charge leaking. Therefore, accurate prediction of Stirling engine power output through theoretical analysis is complex and costly. Emerging machine learning algorithms like Gradient Boosted Regression Trees (GBRT) can offer new approaches to solve this problem. The GBRT model consists of multiple decision trees that branch by exhausting thresholds for all features under study to find the best split structure for data regression, and the principle of GBRT gives it the natural advantage of finding a wide range of distinguishing features and combinations, and a powerful generalization capability. A GBRT forecasting model is thus constructed to model the output power of Alpha-type Stirling engines. Test data from the General Motors 4L23 Stirling Engine are applied as the training and test set. Results from the random test set accounting for 25% of the total samples indicate that the GBRT model has a prediction accuracy of 96.23%. Furthermore, a regional microgrid containing Stirling engines, photovoltaic panels and batteries for industrial waste heat recovery is constructed and an evaluation system for energy supply performance is also established. Finally, based on the proposed power output model, multi-objective optimization based on improved NSGA-II is implemented, providing guidance for industrial application of Stirling engines.

In order to ensure the stability of battery management power system, improve the reliability of on-board electronic products, and ensure the stability of thermal energy recovery power system, the author proposes an electromagnetic compatibility optimization scheme based on wiring harness, power module, and PCB noise, taking the battery management system of vehicle electronic components as an example, the role of electromagnetic compatibility on products is described, the hardware circuit is analyzed and designed by electromagnetic compatibility design theory to ensure the reliability of vehicle components. The electromagnetic stability of the power battery is guaranteed through the electromagnetic compatibility optimization analysis of the battery management system, so as to achieve more stable battery management. The experimental results show that each module of the battery management system works stably, and the disturbance degree test shows that the resonant noise of the battery management system disappears, and there is no obvious narrowband electromagnetic disturbance, and the overall value is below the limit of 20 dB. In conclusion the electomagnetic compatibility optimization scheme can effectively ensure the stability of the battery management power system, and indirectly ensure the stability of the heat recovery power system. [ABSTRACT FROM AUTHOR]

In order to realize the condition monitoring of the motor "anytime, anywhere", improve the detection accuracy and shorten the detection time, the author proposes a fault signal processing and diagnosis system for the motor heat recovery system based on the IoT. That is, based on the IoT technology, a mobile terminal oriented motor remote monitoring and fault diagnosis system, the sensing layer of the system collects real-time motor operation status data, and the transmission layer realizes data transmission, cloud storage and response to data requests from the application layer, finally, at the mobile end, the motor running status and diagnosis results are displayed through charts and text, so as to realize remote monitoring and fault diagnosis of the motor. The experimental results show that the accuracy of fault diagnosis test of GA-SVM in mobile terminal is more than 90%, and the running time is less than 30 ms, and the running time is very short. It proves that the mobile terminal uses the fault detection method based on GA-SVM model with high accuracy and short detection time, that is, the fault signal processing and diagnosis accuracy of the motor heat recovery system of the IoT is high and the detection time is short. [ABSTRACT FROM AUTHOR]

The increased efficiency of solar air heaters has been of great importance in recent years. In this study, the effects of environmental parameters on the performance of a new generation of combined solar air heaters were investigated. Using a novel method in an optimization algorithm, the mixing ratio of fresh air and heated air from this type of heater's reheat system was optimized. The differential equation was modified for this geometry and boundary conditions. As part of the study, the heat recovery system and the preheating of inlet air were applied to increase the efficiency of the air heater. A version of the air heater with a heat recovery system and a version without one were analyzed using Reynolds numbers in the range of 1000 to 8000. In addition, the recovery and preheating cycles were set to close and open, respectively. Note that an air heat exchanger is responsible for transferring the recovery system's fluid energy to the air heater inlet fluid. The calculations of the numerical modeling of air heaters and closed-cycle recovery systems were independently performed in this study. The research study's results showed that adding a recovery system to a solar air heater increased the efficiency and the Nusselt number by 15.23% and 7.8%, respectively. The mean temperature of the air heater was dependent on the mixing rate between fresh inlet air and heated air in the heat exchanger in the recovery cycle. In addition, the results indicated that through optimization, the Nu could be increased up to 23%. [ABSTRACT FROM AUTHOR]

In recent years, there has been a risen interest in heat recovery systems for building applications due to concerns about the energy crisis and global climate change. In this paper, the intention to understand the performance of a window thermoelectric heat pump/heat recovery system (Ecopump) for heating has been developed. An overview to the prototype design, heat transfer model, experimental parameters and environmental feasibility is discussed. The variation of MATLAB modelling results followed the same regularity as the experimental results. The MATLAB model along with Revit has been used to simulate the Ecopump's performance when installed in a sustainable house in the UK. From the calculation, Ecopump can provide 670 kWh heating energy and reduce 90.6 kg CO2 emissions per year. The proposed Ecopump system combined with window frame could be a promising technology to enhance space heating for domestic buildings while reducing energy consumption during daily ventilation. Further in situ experiments should be conducted to explore its comprehensive performance in the future. [ABSTRACT FROM AUTHOR]

Abstract Conforming to the factor characteristics of electricity–water cogeneration power plants, an improved multieffect desalination (MED) and reverse osmosis (RO) are the most current techniques for seawater desalination. A principal change between these operations consists of their various energy requirements, thermal energy for MED and mechanical energy for RO plants. The main improvement ideas of RO and MED are the recovery of large quantities of heat produced during the production of sulfuric acid, which exhibits an exothermic reaction where a part of this heat will be used for the thermal power plant and subsequently reverse osmosis and another amount of heat recovery system will be used to desalinate seawater by the MED system. In this work, the sulfuric acid is used to recover heat energy; this energy is used in a hybrid system of RO–MED in order to desalinate the seawater. A thermodynamic steady-state study of this system is investigated to select the optimum cogeneration system. These improvements could make the benefits of cogeneration to the energy consumption of an RO and MED which will be remarkably reduced.

The aim of this work is to investigate a heat performance of a Multi-Layered Oscillating Heat Pipes Heat Exchanger (ML-OHPHE) for the application of heat recovery in heating, ventilation and air conditioning systems (HVAC systems). The heat exchanger is investigated experimentally under different conditions of heat loads and filling ratios. The experimental data results are compared to the data obtained from Honeywell’s UniSim® Design Suite software. In the end the NTU analysis of the ML-OHPHE is done and a value of overall heat transfer coefficient is calculated. The results of the experiments indicate that the ML-OHPHE could serve as a completely passive heat transfer device in the application of heat recovery in HVAC systems.

In this study, the convective drying process on the stenter machine used natural gas as fuel was examined in terms of energy saving. The fuel consumption in the drying process of wool fabric with and without heat recovery from exhaust air of stenter was determined. It was shown that the fuel consumption in stenter can be decreased significantly by the use of heat recovery exchangers. According to the results minimum fuel consumption was observed at inlet drying air temperature of 180 °C and humidity ratio of the exhaust air of 0.08 kgy/kga. In this condition fuel consumption decreased from 205.3 m3/h to 177.3 m3/h by using heat recovery exchanger. The fuel consumption of drying systems reduced by 13.6%. [ABSTRACT FROM AUTHOR]

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Conforming to the factor characteristics of electricity–water cogeneration power plants, an improved multieffect desalination (MED) and reverse osmosis (RO) are the most current techniques for seawater desalination. A principal change between these operations consists of their various energy requirements, thermal energy for MED and mechanical energy for RO plants. The main improvement ideas of RO and MED are the recovery of large quantities of heat produced during the production of sulfuric acid, which exhibits an exothermic reaction where a part of this heat will be used for the thermal power plant and subsequently reverse osmosis and another amount of heat recovery system will be used to desalinate seawater by the MED system. In this work, the sulfuric acid is used to recover heat energy; this energy is used in a hybrid system of RO–MED in order to desalinate the seawater. A thermodynamic steady-state study of this system is investigated to select the optimum cogeneration system. These improvements could make the benefits of cogeneration to the energy consumption of an RO and MED which will be remarkably reduced. [ABSTRACT FROM AUTHOR]

Taiwan is located in the subtropical zone where the summers are hot and humid. The demand for comfort and quality of life in this zone is increasing. Air conditioning equipment in Taiwan has transformed from a luxury item into a basic necessity, resulting in a growing demand for small, consumer air conditioning units. Attractive, low-noise, small, and split-type air conditioning systems have become popular in the residential air conditioning equipment market. In this study, we used a heat recovery system to recover heat from air to increase the system hot and cold side efficiency and reduce the carbon footprint of smart buildings. The improved wall mounted evaporator combined with a central monitoring system is different from the typical AC unit evaporator that makes the system much more efficient. [ABSTRACT FROM AUTHOR]

In the present study, five configurations of integrated system are introduced and comprehensive thermodynamic modeling and analysis for different arrangements are carried out. An organic Rankine flash cycle (ORFC) and a thermoelectric generator (TEG) are integrated with a real city gate station (CGS) to recover the thermal energy of exhaust gas at 400 °C in an indirect water bath heater (IWBH). The new aspect of the present research is proposal the novel arrangements of the TEG modules, ORFC and IWBH to improve the thermal performance of the CGS integrated system. Energy and exergy analyses employed to evaluate different arrangements of integrated systems. Comparative analysis of different suggested systems revealed that integrated system including IWBH, ORFC and TEG modules with placing the TEG modules after ORFC (Case V) shows better performance. Due to the better performance, Case V is considered for more studies. Under the given condition for the selected case, in a complete year, results indicate that the maximum and minimum values of electrical output power for TEG modules is 132 W and 100 W and for ORFC is 11.5 kW and 2.1 kW. Also, the parametric study of the Case V inferred that with increasing the amount of excess air form 50%–200%, the fuel mass flow rate increased by 35.6% which ultimately leads to a reduction in thermal efficiency of the system. The results suggests that proper arrangement of TEG modules and ORFC in the IWBH can improve the total thermal efficiency as well as the total electrical output power. Analyses of different proposed arrangements, also indicates that with the use ORFC and TEG modules in the worst and best cases 2.284 kW and 5.904 kW electrical energy can be recovered from the IWBH in the CGS. Image 1 • Provide an adopted solution to exhaust waste heat recovery from a city gate station. • Placing the TEG modules after ORFC evaporator is the best configuration for system. • Thermodynamic assessment of system based on six effective design parameters. • There is an optimum value for flash pressure ratio for ORFC between 0.2 and 0.8. [ABSTRACT FROM AUTHOR]

This study aimed to improve equipment in steel industrial in order to save energy, protect the environment, decrease costs, and develop the commercialization improvements. The energy of combustion gases in the reformer box is used to preheat the main air, natural gas, and feed gas in the heat recovery system. The scale-up of process equipment and incorporation of new technologies at the Khouzestan steel company (KSC) in Iran, resulted in their ironmaking plants' capacity increasing from 550,000 to 800,000 ton/year in 2015. Furthermore, this method could prove profitable for old direct reduction ironmaking plants as well. The modifications include changing the reformer tubes' diameter to increase the rate of reducing gas flow, increasing the number of process gas compressors from two to three, improving the top gas scrubber capacity, and modifying the shaft furnace refractory thickness to the thin wall. (The internal diameter of the furnace was increased from 5000 to 5130 mm.) To use the flue gas energy, the arrangement, size, and number of tube bundles were altered in heat recovery system (HRS). The reformer and heat recovery system were simulated with Aspen HYSYS software. The simulation results were relatively in good agreement with the experimental data. In this research, practical results with a real implementation in direct reduced ironmaking plant show equipment improvement that can reduce energy consumption and carbon dioxide emissions. The production tonnage increased by 28.15%, and the energy consumption decreased by 13.71%. However, the amount of carbon dioxide in the flue gas decreased by 9.55%. The flue gas exit temperature from HRS dropped by 152.2 °C. The calculation of the net present value (NPV) and present value (PV) shows that the investment cost will be returned in 4 years. [ABSTRACT FROM AUTHOR]

This article presents a field test of how deep renovation affects indoor climate quality. The studied apartment building was built in 1968 and is located in Finland, within the Nordic climate zone. The deep renovation included façade repair with extra insulation, new windows with trickle vents, new balcony glass and doors, and the installation of an exhaust air heat pump into the existing mechanical exhaust air ventilation. The indoor climate conditions and building envelope tightness were measured before and after the renovation. As a result of these energy renovation measures, the building envelope tightness improved by nearly 40% and the uncontrolled supply of air (draughts) decreased by approximately 24%. The overall energy consumption of the building decreased by 45%. Above all, the long testing period gives credibility to the study. The field test brought up the challenge of supplying an adequate amount of fresh air. This article highlights the fact that windows are part of a mechanical ventilation system if fresh air is not controlled by being led through inlet ducts. The supply air flow and volume must be ensured by correctly dimensioned valves, and therefore we stress the importance of the technical cooperation of technical designers.

November, 12-13th, in Saint-Petersburg the 7th International congress "Energy efficiency. XXI century" took place. The reports were done in breakuo groups according to the various aspects of energy efficiency challenge: HVAC systems, water supply and sewerage systems, gas supply, energy metering. One of the grourps was devoted to thermophysics of buildings and energy effective design of building envelope.

The Midrex office space has been designed for a collaborative environmental work, with an open floor plan and numerous meeting rooms and areas for discussion. PERED® Direct reduction technology is the new technology in the world. Iran developed PERED® direct reduction technology for decreasing capital cost and energy saving. Iron oxide pellets are reduced in the shaft furnace. Top gas return from furnace after cleaning in scrubber is divided into fuel and process gas. Process and natural gas are mixed together (feed gas) after preheat in heat recovery system. Reducing gas is generated in the reformer by reacting methane (CH4) with water vapor (H2O) and recycled carbon dioxide (CO2) in reformer tube. Flue gas is produced due to combustion of gases in the reformer box. Some changes and improvement in equipment have been done. Reformer tubes changed from 8 to 10 inch and reformer box volume is decreased. Process and seal gas compressors are changed from Aerzen rotary lobe type to centrifugal Siemens type. Shaft furnace has a new design and internal furnace diameter is variable in terms of furnace diameter. China hat equipment replaced upper cluster breaker. Elimination of upper cluster breaker is done without any problem for movement of material in the furnace. It is affirm that it does not create any cluster in PERED® technology. Tube bundles arrangement is developed and one steam tube bundle is increased. [ABSTRACT FROM AUTHOR]

Harga minyak dunia cenderung mengalami peningkatan dalam beberapa tahun terakhir sehingga manusia berfikir untuk memanfaatkan setiap penggunaan minyak bumi. Dengan berkembangnya teknologi saat ini waste energy yang berupa gas hasil pembakaran pada engine dapat dimanfaatkan menjadi bentuk energi lain menggunakan heat recovery system. Pada tugas akhir ini dilakukan desain sebuah heat exchanger tipe circular tubes continuous plate fin dengan susunan tube aligned yang digunakan untuk menyerap waste energy yang berupa exhaust gas. Untuk mendapatkan dimensi desain yang sesuai digunakan metode ΔTLMTD. Metode ini digunakan untuk menentukan nilai dari overall heat transfer desain dari heat exchanger, kemudian dilakukan perhitungan untuk nilai overall heat transfer hitung. Setelah didapatkan nilai dari overall heat transfer secara desain dan hitung maka dilakukan iterasi untuk mendapatkan dimensi heat exchanger yang memiliki nilai error paling kecil antara nilai overall heat transfer desain dan hitung. Untuk pengujian performa dari heat exchanger yang telah didesain maka dilakukan variasi kacepatan exhaust gas yang melewati heat exchanger, yaitu 0.4 m/s, 0.3 m/s, dan 0.2 m/s. Exhaust gas yang digunakan memiliki temperatur 280oC. Pada tugas akhir ini didapatkan desain compact heat exchanger dengan dimensi panjang 0.38 m, lebar 0.45 m, dan tebal 0.04m. Setelah dilakukan pengujian dengan memvariasikan kecepatan dari exhaust gas yang melewati heat exchanger maka didapatkan bahwa nilai dari qaktual dari heat exchanger mengalami kenaikan dengan bertambahnya reynolds number akibat bertambahnya kecepatan exhaust gas, kemudian nilai dari effectiveness akan mengalami penurunan untuk setiap kenaikan dari reynold number exhaust gas. Selain itu nilai dari NTU heat exchanger juga mengalami penurunan dengan bertambahnya reynold number exhaust gas. Untuk nilai overall heat transfer dari heat exchanger yang didesain akan mengalami kenaikan akibat bertambahnya nilai reynold number exhaust gas.

In this study, two heat recovery systems, a Rankine cycle (ORC) and a trans-critical CO 2 cycle (tCO 2 ), were applied to a micro gas turbine(MGT) and their performance was compared. The off-design performance of the two bottoming cycles with the load variation of the MGT was also analyzed. The performance curve, the effectiveness-NTU method, and the Stodola’s equation were used to model the off-design operations of all bottoming cycle components, such as a pump, a turbine and heat exchangers. According to the calculations, the power output of the ORC was higher than that of the tCO 2 cycle when the MGT operated at a full load. On the other hand, because the power output variation with the MGT load change is larger in the ORC, the power output of tCO 2 becomes larger when MGT operates at a part load below 75%. Therefore, the tCO 2 is suitable for a heat recovery system utilizing MGT exhaust gas in places where the MGT needs to operate at low loads during many of its operating hours. On the other hand, the ORC is more suitable in applications where the MGT can operate at near full load conditions. [ABSTRACT FROM AUTHOR]

Heat loss from rotary kilns accounts for certain amounts of the total energy consumption in chemical and metallurgical industries. To reduce the heat loss, a parallel and a series-parallel heat recovery systems with nine heat recovery exchangers are proposed to preheat the cold water in this paper. Experimental measurements are carried out to determine the heat transfer coefficient equations of each heat recovery exchanger. Then, the heat recovery systems are analyzed to deduce the mathematic relation between the design parameters and the system requirements, i.e. the temperatures and heat transfer rates of the nine heat recovery exchangers. The total heat transfer area, the total power consumption and the entropy generation due to heat transfer and fluid flow are set as the objective functions in four multi-objective optimization (MOO) cases. With the aid of the genetic algorithm in the Matlab 2015, the optimized operational and structural parameters are obtained. Finally, the MOO results are compared with that of the single objective optimization (SOO) method and the original values. The optimization results show that the MOO method are more suitable for the operational parameters design of the heat recovery systems compared with the SOO method. The required total heat transfer area and the total power consumption are decreased by at least 12.1% and 13.7%, respectively. Besides, as the entropy generation due to heat transfer and fluid flow decrease in the MOO cases, the corresponding heat transfer area and power consumption of the heat recovery system decrease, respectively. [ABSTRACT FROM AUTHOR]

Waste-heat utilization holds great potential for cleaner production by improving energy efficiency, reducing energy usage and enhancing engineering functionality of an industry. Utilization of waste-heat is highly neglected in textile industries of the developing countries. This study quantified the energy and cost saving potential of waste-heat utilization in textile industries with several case studies. It focused on the common waste-heat sources and readily implementable technologies considering both technical and economic aspects. A waste-heat recovery boiler with a capacity of 2.70 t/h ran by hot exhaust from onsite electricity generators was estimated to save annually 15,094 MWh of energy and energy cost of USD 141,280. Installing economizer reduced 4.9% of boiler fuel consumption. Approximately 10% of energy used in stenter-setting machines was saved by installing a heat-exchanger that extracted waste-heat of stenter exhaust to preheat fresh air supplied to stenter operations. A counter-flow heat-exchanger was set up for utilizing waste-heat of dyed waste water. The yearly energy saving potential was 5716 MWh along with minimizing annual energy cost of USD 47,100. A proper stem-condensate recovery system reduced water loss and 10.50% of energy saving was achieved for steam production. [ABSTRACT FROM AUTHOR]

The current study was aimed to design, manufacture and examine a solar heating-drying system experimentally. The heat pipe evacuated tube collector in this system, in addition to supplying the required energy for water heating, supplied the energy needed for a dryer. Moreover, a water heat recovery system was considered for the dryer to enhance the overall efficiency of the system and to make maximum use of solar energy intake. Also, a mathematical model was developed for the energy and exergy analysis of the collector as well as validation with experimental results. In order to simulate the hot water consumption, the consumption pattern of a students’ dormitory hall was used for the case study. The given system was tested under the weather conditions of Sanandaj city and the obtained results indicated the effectiveness of the heat recovery system. The findings showed the optimal number of collector pipes to be 15. Fluctuations of fluid temperature during hot water discharge and replacement with cold water caused fluctuations in collector outlet fluid temperature. Also, a direct association was observed between hot water consumption pattern and system performance. The changing trend of exergetic efficiency was ascending over time. At the end of the day, this efficiency reached its maximum level, about 10.6%. The performance of exchanger was highly dependent upon the ambient temperature and in the volumetric flow rate of 0.0328 m 3 /s, the maximum outlet air temperature of dryer was about 45.5 °C. Also, maximum use of the auxiliary system was reported in the early morning (1.5 h), which was reduced over time. After 14:00 pm, the solar system was able to supply the required energy for the system individually. Finally, the findings of regression analysis showed the most accurate equation for expressing the effectiveness of the dryer as a function of environmental and functional parameter of x (which is equal to ( T w , i − T amb )/ G ) expressed as ε = 112.21 x 3 − 47.095 x 2 + 5.8257 x + 0.1139. [ABSTRACT FROM AUTHOR]

The current study designed, constructed and experimentally evaluated a heat-pipe evacuated tube solar dryer with heat a recovery system in which water was used as working and recovery fluid in the solar and dryer loops, respectively, and air was used as intermediate fluid in the dryer section. The heat recovery system was used to enhance the overall efficiency of the system and to make maximum use of solar energy intake of the dryer. The hot water in the storage tank, which is heated by the solar loop, is sent to the dryer, depending on the system requirement, and its heat in the heat exchanger is delivered to the blown air. The heated air enters the main chamber of dryer, where the drying products exist. This system was tested in the weather conditions of Sanandaj city and the obtained results indicated the effectiveness of heat recovery system. In volumetric flow rate of 0.0328 m 3 /s, the maximum outlet air temperature of dryer was approximately 44.3 °C. At the end of the day, the exergetic efficiency of the system reaches its maximum rate, approximately 11.7%. Using regression analysis, the most accurate equation for expressing the effectiveness of dryer was obtained. [ABSTRACT FROM AUTHOR]

The supply of stable and reliable power is the main challenge that renewable power plants must tackle. Concentrating Solar Power (CSP), among renewable energies, is one of the most appropriate for large-scale energy production since it can efficiently store heat by means of Thermal Energy Storage (TES) systems. However, under unfavorable meteorological conditions, they may not be enough to satisfy the thermal demand of the power plant. With this aim emerges the HYSOL project, which presents an innovative hybridization configuration of CSP and biogas for a 100% renewable power plant. The demonstrator of this technology includes a gas - molten salt Heat Recovery System (HRS), a virtual gas turbine, a molten salt tank and an air cooler. The design of an operation and training tool for the HYSOL project, which includes a dynamic model of the demonstrator, is essential to evaluate the transient response, to test control schemes and to train plant operators. The design of such tool is described in this paper. [ABSTRACT FROM AUTHOR]

Heat loss from the shell of a rotary kiln accounts for a certain proportion of total energy consumption. In order to reduce heat loss, a practical heat recovery system with nine heat exchangers is proposed to preheat water in this paper. We first propose a mathematic model to analyze the shell temperatures and heat loss rates of several regions on rotary kilns. Integration of theoretical analyses and experimental measurements yields the temperatures and heat transfer rates of heat exchangers, i.e. the design requirements of the nine heat exchangers in the practical system. Secondly, an optimization model is formed to describe the relation between design parameters, i.e. heat transfer area and mass flow rate of each heat exchanger, and system requirements without introducing any intermediate temperatures. With the aid of the Lagrange multiplier method, the optimal design parameters are obtained. Finally, an optimization case of the practical system is studied. The results show that the heat recovery system should meet the requirements of chemical reactions in rotary kilns and mechanical characteristic of shell. The required total heat transfer area of the system after optimization is reduced by 15.6% compared to the value before optimization. As the total mass flow rate increase and inlet temperature decreases, the required heat transfer area decreases while the mass flow distribution ratios remains unchanged. [ABSTRACT FROM AUTHOR]

An energetic and exergetic analysis is conducted on a Steam Turbine Power Plant of an existing Phosphoric Acid Factory. The heat recovery systems used in the different parts of the plant are also considered in the study. Mass, energy and exergy balances are established on the main compounds of the plant. A numerical code is established using EES software to perform the calculations required for the thermal and exergy plant analysis considering real variation ranges of the main operating parameters such as pressure, temperature and mass flow rate. The effects of theses parameters on the system performances are investigated. The main sources of irreversibility are the melters, followed by the heat exchangers, the steam turbine generator and the pumps. The maximum energy efficiency is obtained for the blower followed by the heat exchangers, the deaerator and the steam turbine generator. The exergy efficiency obtained for the heat exchanger, the steam turbine generator, the deaerator and the blower are 88%, 74%, 72% and 66% respectively. The effects of High Pressure steam temperature and pressure on the steam turbine generator energy and exergy efficiencies are investigated. [ABSTRACT FROM AUTHOR]