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Este trabajo de investigación, tiene como objetivo mejorar el desempeño de una instalación solar de acondicionamiento de aire por absorción, por medio del diseño de un sistema de control simple, para fácil implementación. Esta instalación fue diseñada por E. Quintana (2012) en TRNSYS, un programa de simulación de sistemas. Con la visión de una futura implementación, un análisis de desempeño del Chiller de absorción se llevó a cabo en base a los resultados de la simulación del trabajo precedente. Se encontró que su desempeño no alcanza los rangos de operación segura dentro del tiempo de operación diaria, cada vez que el sistema se inicia. Basado en esto, el trabajo propuesto abarca el diseño de un sistema de control que permita mejorar el desempeño del Chiller de absorción, desde el punto de vista de seguridad de éste último y la reducción del consumo eléctrico de la instalación. La operación segura del Chiller se alcanza cuando éste y todo el sistema, operan dentro de los rangos nominales indicados por el fabricante. Los resultados indicaron que los parámetros a optimizar son las temperaturas del agua que entra al generador y al acumulador térmico. Empleando las estrategias de control diferencial On-Off y Feedback, los resultados de las simulaciones muestran que el primer objetivo fue alcanzado. Por el contrario, el segundo, no se logra alcanzar ya que la energía proveniente de la fuente solar no logra suplir las necesidades del Chiller dentro del tiempo de operación diaria.

Chillers play essential roles in the heating, ventilation and air conditioning (HVAC) systems to ensure the required thermal comfort. To reduce the operational risk such as faulty operation or ener...

Hybrid renewable polygeneration systems are regarded as key solutions for the sustainable energy supply of buildings. While solar heating and cooling comprises a wide range of technologies, there has been limited research on the combined production of power and cooling only, with little or no heat demand. This study designs and analyzes a hybrid solar–biomass ORC-based polygeneration system from energy, economic, and environmental viewpoints. The polygeneration system is designed to cover the electricity and cooling demands of a commercial center located in Zaragoza, Spain. A parabolic trough collector field coupled with thermal energy storage, and an auxiliary biomass boiler supply heat to an Organic Rankine Cycle (ORC), which generates electricity to cover electrical demands and to produce cooling in mechanical chillers. The biomass boiler supports the solar thermal production to ensure a stable and reliable heat supply to the ORC. The system is connected to the electric grid, so that electricity purchases and sales are possible. The equipment sizing is performed with the goal of achieving a high renewable fraction in the total electricity consumed by the commercial center. The analysis of the proposed plant includes the hourly operation throughout the year, complemented by an economic assessment, considering investment and operation costs, and an estimate of the environmental benefits of the plant. Also, a thermoeconomic analysis is developed to determine the cost formation process of the internal flows and final products of the plant. The unit cost of each flow is broken down into investment and operation cost components. Sensitivity analyses of the investment cost, interest rate, biomass price, and electricity selling price discount are made. The results show that, in economic terms, the system is not presently viable, since the cost of the electricity produced (279.07 €/MWh) is much higher than the electricity purchase price (126.70 €/MWh). In environmental terms, the system is capable of displacing 96.1% of the CO2 emissions and 85.6% of non-renewable primary energy consumption relative to a conventional system consuming grid electricity only.

As any innovative development program, magnetic refrigeration still faces many challenges before being widely accepted as an actual replacement technology for cooling. In the last years, more than 50 different types of prototypes of magnetocaloric refrigerators have been presented in literature, with limited cooling power values and/or limited temperature span. This paper presents several assembly details and experimental results of a new proof-of-concept magnetic refrigeration prototype having both a temperature span of more than 20 K and a cooling capacity designed for around 15 kW. It has been made as a part of a pilot project for a large industrial partner to be used for an industrial process. The obtained experimental results have been measured and validated by an exterior independent body. This performance achievement, that we believe to be as the largest rotary magnetic refrigerator ever created, could be a milestone for the future of magnetocaloric chillers.

One of the main disadvantages of conventional fixed-bed adsorption chillers is the low coefficient of performance due to the high voidage of the sorbent beds. The common method, which can help to h...

Performance of varying speed screw chiller is affected by many uncertainties. High precision prediction of its characteristics can guide the chiller to reach a better performance. This study presents an artificial intelligence model named least square support vector machine (LSSVM) with genetic algorithm (GA). Five parameters are predicted with the model, including COP, discharge pressure, suction temperature, suction pressure and cooling capacity. By comparing the simulation results with the test results, this model shows a high precision ability to predict the performance of the on-site chiller. Additionally, a newly control strategy is introduced to help the chiller with optimizing performance. Cooling capacity and superheat degree are separately used as input to train the model to control openness of EXV. The prediction of this control strategy process shows enough ability to predict openness of EXV. The results can be used to guide the chiller to reach better performances by adjusting the corresponding parameters.

The optimal chiller loading (OCL) is one of the most essential issues for saving energy and costs. Because of the pervasive use of chiller systems in the world, even saving a small amount of energy...

This paper addresses the present status of milk procurement practices in India, advancements in milk chilling technology, cleaning operations of milk chiller units and discusses the issues related to Bulk Milk Cooler (BMC) effluent treatment. Analysis of various physico-chemical parameters revealed that BMC effluent has wide variation in characteristics. BMC effluent discharged after every cleaning process are mainly characterized by the presence of high oil and grease (OG BOD3: 500-7700 mg/L), suspended solids (425-2450 mg/L) and dissolved solids (1075-4610 mg/L). Suitability of employing an anaerobic treatment system consisting of settling cum digestion chamber, baffle reactor and up flow media filtration was studied for its efficacy in treatment of BMC effluent at various loadings. The studies indicated that the stand-alone anaerobic-media treatment with OLR up to ~ 2.0 kg COD/m3.d and ~36-40 hours HRT was able to achieve substantial removal efficiencies of 82.77, 81.33, 96.92, and 94.2% for parameters COD, BOD, O&G, TSS respectively. Even though the system worked satisfactorily at higher loadings, it is necessary to adopt a holistic approach with an addition of tertiary treatment considering the complexity and wide variation in effluent characteristics in order to ensure its reuse for various non-potable purposes and ensure environmental compliance.

In line with the increase in the world population, natural gas, which has an increasing share in fossil fuels, is nowadays transported throughout pipelines in the form of liquefied natural gas (LNG) and compressed natural gas (CNG). Natural gas is preferred to be transported with CNG in terms of optimum cost. CNG is reduced to a volume of 1/250 at 200 bar pressure in filling facilities and is transported to multi-element gas containers or gas tankers where pipelines do not reach. Although the highest cost for these plants seems to be gas transportation costs, the design, infrastructure and operational gaps, especially in plant management of the filling facilities constitute the costs that are not significantly visible. In parallel with the costs incurred, in this study, a pre-cooling process was actively applied for cost-based improvement in a bulk CNG filling facility, while operational optimization was aimed passively. The filling process of the facility in 2016 was examined according to real data and pre-cooling was made in 2017 by adding a “chiller” to the filling process to increase the filling rate to tankers. Thanks to the precooling in 2017, the filling amount made to tankers increased by %7.23. In 2018, the filling process was analyzed in detail according to the data of 2017 and the factors affecting the filling rate were determined. According to these factors, the filling operation has been optimized on a cost basis. Filling operations in 2018 have been optimized for factors varying from month to month and even day, such as; temperature conditions, filling method, the structure of gas tankers and filling platforms, ie the effect of the material used, personnel effect and the filling rate of machines like chiller, compressor. After optimization, the amount of filling made in 2018 increased by %4.36 compared to 2017.

Adsorption chillers (ACs) powered by low-grade solar or waste heat energy have attracted increasing research interest due to their low electricity consumption and carbon emission. Ammonia working fluid with a high enthalpy of evaporation and large vapor pressure that is favorable for heat and mass transfer has been commonly used in ACs. Currently, promoting the cooling performance of ACs greatly relies on the exploration of high-performance adsorbent/ammonia working pairs. Metal–organic frameworks (MOFs) have been demonstrated as promising adsorbents for ACs using water or alcohol working fluids. However, the use of ammonia and MOF adsorbents in ACs is extremely challenging due to the difficulties in achieving ammonia adsorption performance and ammonia stability of MOFs. In this study, we evaluated the cooling performance of nine MOF/ammonia working pairs based on the ammonia adsorption data from grand canonical Monte Carlo (GCMC) simulations, from which it was found that NU-1000/ammonia exhibited the highest coefficient of performance for cooling (COPC) of 0.58 and specific cooling effect (SCE) of 560 kJ kg−1, while MIL-101/ammonia showed the highest SCE of 924 kJ kg−1 and COPC of 0.50. Such a trend was further proved by experimental measurements. However, ammonia cycling measurements demonstrated that NU-1000 suffered from a severe reduction in adsorption capacity due to its ammonia instability. In contrast, MIL-101 displayed excellent recyclability in ammonia as well as outstanding cooling performance, suggesting its great potential in AC applications.

A prototype ejector chiller with nominal cooling power of 40 kW, designed according to the “CRMC” criterion, has been tested by our research group since 2011. The prototype has undergone several refinements and finally has been upgraded to R1233zd(E), which is non-flammable, has low-GWP and favourable thermodynamic properties, i.e. “dry-expansion” and moderate pressure at generator. In terms of saturation pressure curve, the new fluid is similar to R245fa, which was previously used in the prototype. Hence, R1233zd(E) has been basically used as a “drop-in” replacement. The ejector chiller was tested at different evaporation temperatures (2.5 to 10°C), typical of air conditioning applications. Saturation temperatures at generator from 95 to 105°C have been selected as representative of waste-heat recovery. The experimental findings prove that the CRMC ejector has a satisfactory performance with the new working fluid.

The current tendency is to fabricate an innovative group of MMC term as HMMCs where different combinations of the materials are choosing in the direction of achieve advanced mechanical properties. In this current exploration intend by manufacturing aluminum union/ Silica/Carbon (Al/SiO2/C) HMMC within mould restrain dissimilar Coldness resources through separate constituent part within liquid state aluminum alloy. In this break up particles are additional varieties as of 4 just before 16 wt% into hierarchy of 4 wt%. The prepared cast composites specimens are as per the American Society for Testing and Materials Standards for mechanical properties.

A cogeneration solar system for a building located in Sabzevar (Iran) is investigated in this study. In this system, a combination of a solar evacuated tube collector field and an auxiliary natural gas burner drive a single effect absorption chiller. Solar energy is also used to produce consuming hot water. Hourly cooling demands of the building were calculated during April to September. In order to perform a more obvious assessment, important parameters such as COP and efficiencies were obtained based on the total cooling load, the total amount of absorbed solar energy and consumed natural gas, and the total produced hot water during April to September. Energetic, exergetic, and economic analyses were performed in order to find the most efficient generator temperature. Considering the results, the minimum consumption of natural gas happened at a generator temperature of 104 ° C while the highest chiller exergy efficiency is observed at the generator temperature of 97 ° C. Also by assuming the required gas fuel to supply the consuming hot water -which is produced by solar energy-as a saving parameter, the economic optimum generator temperature to drive the absorption chiller and to supply the consuming hot water is obtained at the generator temperature of 96 ° C.

In order to reduce energy consumption of the centralized chilled-water cooling system in large buildings, a dynamic control strategy was proposed for cooling plants by modelling and optimization. Combined with the chilled water flow model, this paper analyzed the parallel operation characteristics of the chillers and takes the load distribution as one of the control parameters. Based on the measured data of a typical cooling system that has undergone preliminary energy-saving transformation, the residual neural network is applied to model the relationship among energy consumption, controllable parameters and environmental parameters, and the residual neural network outperforms multi-layer perceptron and support vector regression. To minimize the total energy consumption, the gray wolf optimizer was introduced to optimize the controllable variables of the cooling system. Compared with the energy consumption before optimization, the simulation energy consumption after optimization decreased 10.45% on average, while the energy saving rate is only 7.9% with equal chilled water supply temperature of parallel chillers.

Climate change concerns have made the engineering community care more about environmentally friendly working fluids. Currently, the fluid R134a, which has a high global warming potential, is widely used in chiller applications. In this study, several low GWP working fluids, R450A, R513A, R1224yd(Z), and R1234ze(E), are investigated numerically as alternatives to R134a for comparison of their performance under different operating conditions in a centrifugal chiller application. Both the system level performance and component level performance are presented. Increasing the condensing temperature or decreasing the evaporating temperature can lead to a higher compressor power, and thus a lower COP can be obtained. The effect of superheat is trivial for the system level performance. R1224yd(Z) has the lowest value of volumetric capacity, and R513A has a higher value as compared with the baseline. As for retrofit, R1224yd(Z) can only produce $$\sim 20$$ % of the baseline cooling capacity. As for the compressor size, the R1224yd(Z) value is more than double as compared with the baseline R134a one, and R513A has a compressor size closest to that of the baseline R134a. R450A and R1234z(E) have a slightly higher value in terms of the compressor size. In general, R513A is the best candidate as an R134a alternative.

The dual cooling system at the California State University Los Angeles Hydrogen Research and Fueling Facility is analysed to predict the output hydrogen temperature in different ambient conditions. Initially, the facility was built with a coil chiller T20 cooling, sufficient for occasional fuelings. A flat plate evaporator system was added in series to resolve any issues for multiple fuelings even in the hottest weather. This study was commenced to verify the set points and determine the control requirements for the dual setup in order to inform future designs. A numerical-empirical model of the cooling system was developed by reverse engineering, using the station experimental measurements and database records. The subsystems are characterized separately but validated as a whole system imposing specific and standard operating conditions. The cooling model is tested with different inputs to validate the pre-set parameter variation of the cooling components. Ten scenarios were investigated to evaluate the fueling output parameters, testing two hydrogen temperature input trends (according to the facility initial conditions) and five ambient temperatures (from 15 °C to 35 °C). The simulation results have confirmed that the hydrogen output temperature remains within the range imposed by the SAE J2601 for each scenario studied, around −22 °C and −25 °C.

Investigating the pool boiling process in the absorption chiller generator by studying the valid parameters may enhance the chiller?s COP. In the present study, the transient 2-D numerical modelling of LiBr/H2O solution pool boiling in the generator of the absorption chiller was carried out using the two-phase Eulerian-Eulerian approach, extended Rensselaer Polytechnic Institute boiling model and renormalization group k-? turbulence model. The numerical model was applied on three types of the bare, notched fin, and low fin tubes to investigate the effect of using fin on the boiling heat transfer rate in the generator of the absorption chiller and comparing it with the bare tube. Moreover, the numerical results were compared with the data obtained from the previous experimental studies to validate numerical modelling. A good agreement was achieved between numerical and experimental results. The results showed the evaporation mechanisms in the microlayer, evaporation in the three-phase (liquid-vapor-solid) contact line, and transient conduction the superheat layer for constant thermal heat flux and the three surfaces of the copper tube within a specific period from the boiling point of LiBr/H2O solution. The results also showed that the use of a notched fin-tube and low fin tube increases the non-homogeneous nucleation rate, causes the solution boil earlier than the bare tube, and reduces the required thermal energy in the generator of an absorption chiller.

The key to achieving high efficiencies, high performance, and low costs of adsorption heat pumps/chillers (AHPs/ACs) is to choose a suitable adsorbent. A computational screening of 6013 computation-ready experimental metal–organic frameworks (CoRE-MOFs) is performed for methanol–MOF pairs in AHPs/ACs, and 137 953 hypothetical MOFs (hMOFs) are further directionally screened based on the range of optimal CoRE-MOF descriptors. Compared with the blind screening of CoRE-MOFs (∼13%), ∼80% of hMOFs obtained by the directional screening exhibited high performance in AHPs/ACs, proving the effectiveness of directional screening. Then, the techno-economic analysis (Ctotal) of AHPs/ACs for each MOF was performed based on the equipment cost (Cequipment), cycle cost (Ccycle), and material cost (CMOF). Cequipment accounted for the greatest proportion of Ctotal, but the proportion of Cequipment decreased and the proportion of Ccycle gradually increased as the MOF data set tended to be the materials with better performance. This confirmed the reduction of Ctotal by an effective enhancement of the Ccycle proportion, and that the high manufacturing cost of MOFs would not restrict their widespread use in AHPs/ACs. Among 6 machine learning (ML) algorithms, the random forest could yield the best prediction effect with little effect by the metal type of MOFs, whereas the heat of adsorption and MOF density were two key descriptors to determine Ctotal. 12 lowest-cost CoRE-MOFs and hMOFs were identified for each application, and their average costs in state 2 were only ∼1 USD kJ−1 in AHPs/ACs. Finally, a variant of the well-known MOF (Cu3BTC2) was predicted to possess superior techno-economy, which was confirmed by a parallel methanol adsorption experiment. These comprehensive insights from directional computational screening, ML algorithms to experiment can guide the development of low-cost and high-performance MOFs for AHPs/ACs in a variety of energy conservation and industrial applications.

A critical issue concerning the gas turbine cycle of combined cycle power station is the reduction in net power output considerably with increasing ambient air temperature. The present simulation study aims to improve the performance of gas turbine cycle of combined cycle power station through use the fresh air handling units of mechanical chiller. To obtains the influence of use the mechanical chiller as pre-cooling units on a performance of gas turbine cycle, the thermodynamic analysis are used to simulate the performance of gas turbine cycle for three different operating loads (66.67, 83.33, and 100% full load). Based on results of the simulation analysis, the mechanical chiller which is inserted as a pre-cooling unit can; (i) increase the average monthly net power output by values varying between 7.33-18.17 MW compared to the original case without pre-cooling units; (ii) the rate of improvement in the average monthly net power output varies between 4.6-11% compared to the case without pre-cooling units; (iii) reduce the specific fuel consumption (SFC) by a rate varying between 5.21-10.81 kgfuel /MWh compared to the original case without pre-cooling units; and (iv) the saving in SFC reached to 4.4% compared to the original case without pre-cooling units.

This paper presents a method for data- and model-driven control optimisation for industrial energy supply systems (IESS) by means of deep reinforcement learning (DRL). The method consists of five steps, including system boundary definition and data accumulation, system modelling and validation, implementation of DRL algorithms, performance comparison and adaptation or application of the control strategy. The method is successfully applied to a simulation of an industrial cooling system using the PPO (proximal policy optimisation) algorithm. Significant reductions in electricity cost by 3% to 17% as well as reductions in CO2 emissions by 2% to 11% are achieved. The DRL-based control strategy is interpreted and three main reasons for the performance increase are identified. The DRL controller reduces energy cost by utilizing the storage capacity of the cooling system and moving electricity demand to times of lower prices. Additionally, the DRL-based control strategy for cooling towers as well as compression chillers reduces electricity cost and wear-related cost alike.

Effective chiller fault diagnosis is of great importance for maintaining a better service and energy efficiency. Deep learning proficiently solves some problems challenging Artificial Intelligence and becomes one of the excellent candidates for fault diagnosis recently. This study proposes a novel fault diagnosis strategy for a chiller, which merges simulated annealing (SA) into a deep neural network (DNN) to obtain effective, efficient, and stable performance. The proposed SA-DNN strategy is carefully compared with DNN and back-propagation (BP) network. The results show that SA-DNN enhances the diagnostic accuracy, shortens the running time, and greatly improves the model stability. The optimal network structure has 2 hidden layers (HL) with each layer 64 nodes, and the overall diagnostic accuracy for seven typical faults attains 99.30%. The nodes in the first HL are proved to be dominant over those in the second or behind because the mapping of the second can hardly make corrections if that of the first is deformed already. The global faults are hard to be diagnosed due to the global effect, but the proposed strategy achieves satisfactory results with the highest individual accuracy reaching 99.79% for excess oil and the lowest 97.52% for refrigerant leakage. The features used for diagnosis have an influence on the accuracy of the proposed method.

As renewable energy elucidation, the solar refrigeration of fruits such as date palm is a storage alternate to preserve food in healthy parameters of conditioning. This statistical and numeric study investigates the energy gain cost case around the diverse dimensions’ models of positive cold stores (02, 04, and 06 cold rooms), concerning energetic disparity and numerous financial fluctuations of the applied systems. The results of computation and analysis regarding panels of construction, equipment, consumption, and maintenance for classic, absorption, and adsorption refrigeration systems that conserve dates palm into these three cold stores. In the end, the comparison of technical and economic elements in tables and figures by enumerating their advantages and inconveniences. Classic Bitzer, Absorption WFC SC 5, and Adsorption AG ACS 15 and 08 are models in which their evaluation is relating to their costs. In Biskra, these results mean that adsorption chiller termed AG ACS (15 plus 08) is illustrious by its parameters of simplicity, lifespan, safety, and security, valued to 1147.5 €/m² and median cost up ten years of using is 92972 €.

Solar cooling systems are a promising solution for reducing the electrical consumption of conventional building cooling systems. Among various alternatives, photovoltaic driven vapour compression chillers are currently the most mature and economically feasible solar cooling technology. This study focuses on the semi-dynamic modelling of a vapour compression chiller coupled with a novel refrigerant-phase change material (PCM)-water heat exchanger (RPW-HEX) which replaces the conventional chiller's evaporator, allowing the efficient storage of the produced cooling energy. A custom-build lumped parameter model was developed in TRNSYS and was used to assess the performance of the proposed system on annual basis. Using as benchmark a conventional PV driven vapour compression chiller with electrical storage, the retrofitted hybrid storage system showed improved performance, limiting the cooling demand peaks and enhancing the solar fraction, especially for partial cooling loads. Last, a comparison of the PCM thermal energy storage to conventional batteries was carried out, leading to enhanced performance characteristics for the latter. This study has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 768824. This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.

Most previous studies on adsorption chillers were conducted using the same adsorption and desorption times. Instead, this study analyzed various adsorption/desorption time allocations, and systematically examined the effect of cycle time allocation on system performance. The results provide physical insights for 3-bed adsorption chillers. The effect of hot water temperature and cycle time on the optimum adsorption/desorption time ratio was also examined. Setting the proper adsorption and desorption times was much more important for smaller cycle times. The highest degradation in COP (coefficient of performance) found was 36% at 300 s of cycle time, compared with the conventional 1:1 ratio. When the temperature of the heat source is low, the ratio of adsorption/desorption time was not significantly affected, however, for higher performance at high temperature, a longer adsorption time than desorption time was required.

Progressive solidification is usually considered an effective strategy to reduce the hot tearing susceptibility of a cast component. In this study, special constrained plate castings with progressive changes in cross-section were designed, which enabled progressive solidification. The hot tearing behavior of a newly developed NZ30K Mg alloy (Mg-3.0Nd-0.2Zn-Zr, wt.%) was studied under progressive solidification using various mold temperature distributions and constraint lengths. Of these, a homogeneous mold temperature distribution is found to be the best option to avoid hot tearing, followed by a local low mold temperature distribution (with a chiller), then a gradient mold temperature distribution. Unexpectedly, compared with the homogeneous mold temperature distribution, adding a chiller does not provide any further reduction in the hot tearing susceptibility of the NZ30K Mg alloy. A high mold temperature and a short constraint length increase the hot tearing resistance of cast Mg alloys. Progressive solidification is not a sufficient and necessary condition to avoid the formation of hot tearing. The two key factors that determine the occurrence of hot tearing under progressive solidification are the maximum cooling rate and the constraint length. Decreasing these values can reduce the incidence of hot tearing.

This paper numerically investigates the performance of a high capacity, industrial ejector chiller working with the non-flammable, low GWP refrigerant R1233zd(E). The test procedures adopted to acquire the experimental data are explained in part 1 of this work. Different turbulence models were examined in order to accurately predict the ejector off-design transition and critical pressure. A peculiar difference has been noticed between the numerical results obtained when initializing the CFD simulation from the solution of a case with lower or higher condenser pressure. This difference may partly explain the difficulties in the accurate predictions of the critical conditions reported by this and other works in the literature. A detailed discussion is presented on the nature and possible cause of this phenomenon, which is identified as typical of non-linear fluid dynamics.

Hybrid chiller plants (HCPs) using multiple chillers and different energy sources are highly recommended in several energy applications in non-residential buildings such as hospitals and hotels. Time of use and cooling load profiles are significant factors that should be carefully considered either in chiller plant design or in chiller sequencing operation. This article aims to present an operation planning of HCP which consists of both electric and non-electric chillers. Four operational strategies are proposed and solved to compare their coefficients of performance and economics of running costs. A typical hotel building located on the Nile river in Egypt is selected to perform the current thermal and economic case study. The total cooling load profile of this hotel building is 4000 refrigeration tonnage (TR), which is simulated to optimize chiller sequence of operation and to select optimal design conditions of both numbers for electric and non-electric chillers used in HCP. The results of this comparative study for running cost are defined using various design configurations with different several chiller sequences available for each configuration. Then, the results of COPs, and operational running cost and initial cost are presented in this article also. The comparison aims to find the optimal design and operational sequencing for HCPs on thermal basis and economic analysis which were attached in this article. Recommendations and suggestions for future work are attached at the end of this article.

Chilled water air conditioning system is used to supply cooling systems in large capacity for industrial processes and commercial buildings. Air conditioners contribute more than 60 percent of electricity consumption in buildings. District Cooling System (DCS) technology comprises a central chiller plant which provides advantage compared to local air conditioning system. It has higher efficiency, uses less power in system operation, allows more usable space in buildings, and can be operated with minimum manpower while handling same amount of cooling load. The integration of a chiller with ice thermal storage (ITS) offers more operational flexibility while reducing space cooling expenses. This paper presents a systematic framework for design and operation of District Cooling Plant (DCP) comprising an integrated chiller and ice thermal storage system. The Cooling System Cascade Analysis (COSCA) based on pinch analysis is constructed to determine the chiller optimal size and ice thermal storage capacity. The District Cooling System configuration for this study comprises a cooling tower, chiller (centrifugal, variable centrifugal, glycol) and ice thermal storage system. The application of this technique to fulfil 66,284 refrigerant tonne hour (RTH) cooling load demand from commercial buildings reveals the optimal capacity of the chiller is 3068.91 refrigerant tonne (RT), ice tank rating at 989 refrigerant tonne (RT) and ice tank capacity is 9892.75 refrigerant tonne hour (RTH).

Data-driven simulation models can be used for optimal control and decision making in building systems only if they are developed accurately and reliably. An unsolved issue pertains to the data coll...

Photovoltaic systems combined with electrical compression chillers offer a high potential for energy efficient cooling with a high economic feasibility. They can significantly reduce the energy consumption in the building sector. The main goal of this study is to analyse the performance of a PV solar driven water-water chiller. The novelty of the work relies on the use of a novel system, called photovoltaic evaporative chimney, which aims to increase the efficiency of solar photovoltaic modules by evaporative cooling. The complete solar cooling system consists of four PV panels (1.02 kWp) and a 3.8 kW refrigeration capacity water-cooled chiller. A systematic study was undertaken and nine sets of experiments were conducted in summer conditions of a Mediterranean climate (Spain). The system’s ability to convert the solar energy into refrigeration capacity was observed to be 0.49 on average for the tests performed. The solar contribution (ratio of PV energy consumption to total absorbed energy) was 64.40%. The system produced on average 11.32 cooling kWh per each kWh consumed from the grid. The influence of the ambient conditions on the key performance indicators has been assessed and global correlations for use in more detailed energy analyses have been developed.

Energy storage is widely used in energy flexible buildings, which have great potential for relieving the power imbalance of electrical grids. However, most of the existing energy storage systems are designed for short-term storage, and only a few systems reported for long-term or multi-time scale storage. This paper introduces a new type of multi-timescale cold storage system consisted of a heat pipe-based natural ice storage subsystem and a dual-operation chiller for buildings to enhance their energy flexibility. The proposed system operated in different modes to provide the seasonal cold storage, nighttime chilled water storage, and urgent demand response services, which can be used for relieving the power imbalance in the timescale of the long-term, short-term and real-time respectively. The working principle, system configuration, operation modes, and the implementation of the proposed system for multi-timescale power management, are presented. A case study has been conducted in a building in Beijing to demonstrate the application and effectiveness. Results show that building load factors are greatly improved seasonally (from 19.5% to 49.5%) and daily (from 55.7% to 72.2%), and the power consumption is also considerably decreased (41.2%) during the demand response (DR) event.

This work aims to provide a state-of-the-art review of the performance of combined cycle power plant (CCPP) based on several proposed inlet air cooling systems. Investigators strive to meet the significant need to promote and develop inlet air cooling technologies to recover heat from the wasted energy in the exhaust gasses of the CCPP and diminish the environmental impacts. Various types of cooling systems mainly offer a boost for electric power generation during the peak load hours. The output power of the CCPP directly depends on the mass flow rate of air that flows through the air compressor. Therefore, during extremely hot weather conditions, subsequently, the air density drops, and this leads to a drastic decrease in the power output. This paper reviews available studies investigated the impacts of inlet air cooling systems on the performance of the CCPP. The fogging cooling system contributed by up to 17% in improving the total performance of the CCPP; however, with the use of the evaporative cooling, the performance was enhanced by only 4%. The energy consumption of mechanical chiller compared to that of evaporative cooling is high due to the effectiveness of the evaporative cooler which depends on the humidity of inlet airflow. Further, the mechanical cooling system can provide the CCPP with a cooling effect for around 7-hour on-peak periods. This method increases the gain of the CCPP performance by 13.6%. Ultimately, the CCPP equipped with an absorption chiller demonstrates the best solution to increase the performance by up to 23%.

In this study, approaches developed by previous studies which to improve the characteristic equation method applied to absorption chiller were analyzed and an approach is proposed aiming to obtain a further contribution. A computational code was designed containing the chiller thermodynamic modelling and the characteristic equations obtained by each approach. The modelling results and the characteristic equations results were numerically compared and the COP and heat removed ( Q ˙ E ) deviations between them were calculated. The sequence of approaches aimed to reduce these deviations. The first approach computed the characteristic parameters and used them as constants values. The second approach used a linear adjustment between the minimum characteristic temperature difference (ΔΔtminE) and the characteristic temperature difference. The third approach used the previous approach adjustment, and the following were inserted in the characteristic equations: linear adjustments between ΔΔtminE; SE and the lift temperature (∆tlift), and between ΔΔtminE; SE and the thrust temperature (∆tthrust). The ∆tthrust adjustment obtained the lowest deviations. Using ΔΔtminE obtained directly from the input data, a better linear adjustment was achieved between ΔΔtminE and ∆tthrust. The use of this adjustment was treated as a proposed approach and achieved even smaller deviations. Then, a case study in a commercial chiller was performed with this approach. Most COP and Q ˙ E deviations values obtained in this case study were lower than 5%. Deviations between the manufacturer's datasheet values and the characteristic equations results were lower than 10%. Therefore, it can be understood that this approach can contribute to the characteristic equation method.

A novel centrally heated, externally cooled (CHEC) adsorbent bed is conceptualized, modeled, and tested at a lab scale. It eliminates the need for cooling liquid lines and controls to the adsorbent bed, reducing system complexity and allowing the system to be used over a large range of thermal inputs. The reduction in complexity is achieved by using the external surface of the bed to directly transfer heat to the surrounding air. Such a system is ideal for small-scale waste heat utilization where a chiller tower cost or space prohibitive. The activated-carbon/ammonia working pair is chosen and system performance modeled over a range of waste heat temperatures. Coefficients of performance (COP) of up to 0.1 and Specific Cooling Capacities (SCC) of 4-80 W kg-1 are predicted and demonstrated experimentally for small-scale systems delivering 100 watts of cooling or less. Performance is expected to improve dramatically at larger system scales due to the larger bed-to-auxiliary thermal mass ratios. This concept trades system efficiency for reduced system complexity. It should also improve system reliability and reduce system cost by eliminating valves and pumps required for the cooling system.

A standalone, compact, thermally driven ammonia-water absorption chiller designed to deliver a cooling capacity of 10.5 kW at ambient temperatures greater than 40 °C is presented. Heat and mass exchangers with novel microscale features and geometries are employed to minimize the physical size of the system. A diabatic distillation column based desorber and a shell-and-tube absorber with microscale features are used. Thermodynamic cycle modeling and heat and mass exchanger design methodologies are discussed. The performance of the packaged unit chiller is demonstrated experimentally over a wide range of operating conditions. The system delivered 10.6 kW of cooling at a COP of 0.63 at design conditions in a compact 0.7 m x 0.9 m x 1.0 m envelope. This work validates the scalability of microchannel heat exchanger technology from a proof-of-concept laboratory scale device to a residential-scale absorption heat pump.

In this paper, theoretical investigation of an integrated solar-powered cooling system consisting of commercial photovoltaic/thermal (PVT) collectors and an adsorption chiller is performed. The performance is investigated under different climate conditions of the Middle East such as Alexandria in Egypt, Dubai in United Arab Emirates and Riyadh in Saudi Arabia. System performance parameters including cooling capacities, chiller COP, solar COP, generated electric power and total system efficiency have been investigated. The results of the study for the month of July show that the maximum generated electric power is about 12.55 kW in Alexandria, while the maximum cooling capacity and COP are 8.1 kW and 0.43, respectively in Dubai. Furthermore, the average total system efficiency in a typical day in July is about 0.248, 0.288 and 0.275 in Alexandria, Dubai and Riyadh, respectively.

As global warming and water scarcity issues continue to grow, it is essential to increase resources efficiency for air conditioners and power plants. In order to increase the efficiency, the systems need to be modified to take the advantages of the low night temperature and thermal storage tanks. In this study, the low night temperature and thermal storage tanks effects on the cooling tower is studied using TRNSYS. Using a chiller operating from 8:00 to 16:00 as a case study, hot water from the condenser is partially stored on daytime and cooled slowly during the night. The storage tank volume is optimized by considering two big tanks and five small tanks. The results show that night cooling reduces cooling water temperature by 5.8 °C or 21.8% while the cooling efficiency is increased by 36%. The thermal storage tanks enable to have the low continuous flow rate and help to reduce the fan power by 67.1%. On the storage side, compared to two tanks system, the tanks volume is reduced by 16.5% when 5 tanks are used. In theory this reduction can go up to 50% by increasing the number of tanks and reducing their individual size.