System Coefficient Of Performance Research Articles

Experiments on the characteristics of a sewage water source heat pump system for heat recovery from bath waste

• This non-metallic heat exchanger has better corrosion resistance. • The thermal conductivity of this non-metallic material is higher than that of traditional non-metallic heat exchangers. • The heat transfer coefficient of the nonmetal heat exchanger is less than that of the metal heat exchanger. • The heat exchanger in the sewage tank at different depths affects the adhesion rate of stains on the surface of the device, which is mainly caused by the different water flow rates. • Sewage heat recovery system plays an important role in energy saving and environmental protection. Sewage water source heat pump (SWSHP) systems with energy saving and environmental protection advantages have been widely studied, and sewage heat exchangers are an important part of SWSHP systems. Problems such as scale formation, difficulty in cleaning, and rapid decrease of their heat transfer coefficient with time have long been associated with SWSHP systems. With these in mind, in this study, we build a SWSHP system for the recovery of heat from waste using a waste water bath experimental platform, and applied a new, rare earth element (REE) non-metallic immersion sewage heat exchanger, The heat exchanger has heat transfer ability in actual working condition, as well as the operational features of a SWSHP system. From test data, the attenuation of heat transfer and the heat transfer coefficient of the sewage heat exchanger with time were analyzed. An attenuation formula of the heat transfer coefficient was determined using a logistic function. The results show that during 90 days of continuous operation, the surface heat transfer capacity decreased by approximately 7.8%, and the rate of decline over time was much lower than that of traditional heat exchangers. The results show that the system can produce hot water at 40.4–60.6 ℃, and the highest system coefficient of performance (SCOP) of the system is 5.65. Our study shows that varying the depth of immersion of the heat exchanger in the water pool affects the heat transfer ability of the heat exchanger. Results show that when the heat exchanger is closer to the pool surface, water-flushing action is strong. With a long runtime, the heat exchanger’s heat transfer ability has a slower rate of decline over time. Based on the test results, the energy consumption of the system was analyzed, and the energy saved by the continuous operation of the system for one year was determined to be equivalent to that of burning 4.29 × 10 4 kg of standard coal.

Performance of a Hybrid TEG/Single Stage Ammonia-Water Absorption Refrigeration Cycle with a Combined Effect of Rectifier and Condensate Precooler

In this article, a single stage ammonia-water absorption refrigeration cycle integrated with thermoelectric power generators driven by evacuated tube solar collectors is presented and investigated. The working fluid is ammonia-water solution, and the hybrid system was modeled, and analyzed using EES software. The system coefficient of performance (COP) was found to increase with increasing the generator temperature. From the results obtained, when the cycle operated with 0.99 ammonia mass fraction, it was found that the best location of the thermoelectric generators is at the rectifier between the generator and the condenser where the value of COP exceeds 0.82 at temperature difference across the TEG of 60℃. The other locations, between condenser-evaporator and evaporator-absorber, show similar performance.

Application of ohmic cooking to produce a soy protein-based meat analogue

The potential of ohmic cooking for the production of a soy protein-based meat analogue was investigated. The ohmic cooking system subjected the meat analogue to a 30 V/cm electric field, enabling rapid heating within 0.66–0.87 min, depending on the cooking temperature. The sample was ohmically cooked using different combinations of temperature (70, 80, 90, and 100 °C) and holding time (1, 3, 5, and 7 min). A cooking temperature of 100 °C yielded the highest system performance coefficient (SPC) of 0.75. The electrical energy consumption was analyzed in terms of total energy consumption and holding energy consumption, which was minimal compared to the former. Hardness and gumminess increased as a function of cooking temperature and holding time. Cooking at 100 °C for 3 min yielded the appropriate meat analogue textural quality (hardness = 104 N), similar to that of commercial chicken nuggets and restructured beef steaks. The pH of ohmically cooked meat analogue ranged from 7.27 to 7.53, but was not influenced by cooking temperature and holding time. Increased cooking temperatures and longer holding times resulted in enhanced yellowness of the internal color. This study showed the potential of ohmic cooking to rapidly produce meat analogues with good quality attributes.

Integration of a solar-powered absorption chiller for performance enhancement of a supermarket CO2 refrigeration plant

CO2 refrigeration configurations are the most viable solution for commercial refrigeration plants, which are however accompanied with energy challenges due to their low energy efficiency when operating under high ambient temperatures. This study examines the coupling of a CO2 booster system with a solar absorption chiller, used to sub-cool the CO2 of the main cycle. The refrigeration system under study is projected to cover the cooling requirements of a supermarket refrigeration plant with an installed capacity of 80 kWR for the medium and 20 kWR for the low-temperature circuit, in the region of Athens, Greece. The investigated process involves utilization of an absorption chiller module with 60 kWR of cooling capacity working with a LiBr-H20 pair powered by heat produced in fifty evacuated-tube solar collectors with a total collecting area of 115 m2. The energy performance analysis was based on validated numerical models developed in MATLAB using the CoolProp library. Through parametric analysis the coefficient of performance (COP) of the proposed topology was compared to the COP of a conventional booster system under constant low (450 W/m2) and high (800 W/m2) incident solar radiation for the temperature range 1–40 °C, resulting in maximum COP increments of 26.44% and 47.34% respectively. Performance simulation on an annualized basis was also conducted, by using the average hourly values of ambient temperature and solar radiation for every month of the year. The results showed that in comparison to the conventional booster system, the sub-cooling rates achieved a maximum increment of COP of 47.48% hourly and 16.36% monthly for August which is the warmest month of the year. Annual electricity consumption decreased by 8.93%, resulting in an energy savings of 30.19 MWh/year.

A current efficiency model coupled with desiccant molecular weight for electrodialysis regeneration in liquid desiccant air-conditioning systems

Liquid desiccant air-conditioning system is an energy-efficient choice for heat and moisture independent treatment in buildings, especially for the large dehumidification load. Electrodialysis regeneration is a novel and reliable regeneration method for liquid desiccants, which is suitable for hot and humid climates. In this paper, the performance of the electrodialysis regenerator for regenerating lithium chloride and lithium bromide solutions was studied experimentally, and the current efficiency of the electrodialysis regenerator for regenerating these two solutions was compared. Through analysis, the solute molecular weight was coupled into the current efficiency model, and a new current efficiency model of electrodialysis regenerator for regenerating these two solutions was established, which considers the solute molecular weight of liquid desiccant and can be extended to more liquid desiccants in the future. Furthermore, the performance of the liquid desiccant air-conditioning system using electrodialysis regeneration with these two solutions is compared based on this model. The results show that when lithium chloride solution is applied as liquid desiccant, the system performance coefficient (COP, ratio of cooling capacity to energy consumption) is between 1.16 and 4.49, while the performance coefficient of the system is between 2 and 8.3 when the system uses lithium bromide solution.

Energy Saving Control of Integrated Energy Multi-Energy Complementary Coupling Space Heating System Based on Fuzzy Theory

Because the traditional solar-ground source heat pump heating system uses temperature difference controllers to control most, it causes the problem of large energy consumption of the equipment. In order to improve such problems, the complexity of the space heating control system is considered comprehensively, and the fuzzy strategy is used to improve the previous control system. TRNSYS was used to build a heating system simulation model, MATLAB was used to build a solar heating system fuzzy controller model, and the two models were coupled to jointly simulate the internal temperature change and energy consumption of the space under the same environmental conditions and different controllers. Experiments show that under the design conditions, the solar collector is greatly affected by the light, the temperature of the hot water storage tank is controlled between 58°C and 65°C. Using the traditional temperature difference controller, the system COP (Coefficient Of Performance) is low and the energy consumption is large, and the economic benefits are not high; the use of the fuzzy controller can increase the system COP by 6.1%, reduce the energy consumption by 22.85%, and save 8.71 yuan in the daily economic benefits of the system.

Compression-assisted decomposition thermochemical sorption energy storage system for deep engine exhaust waste heat recovery

In the context of the stringent automobile emission legislations, this paper proposes a novel compression-assisted decomposition thermochemical sorption energy storage system for recovering engine exhaust waste heat, which is utilized to produce cooling capacity for a refrigerated vehicle. In this system, the desorption pressure of sorbent can be flexibly adjusted by changing the suction pressure of compressor embedded between the sorption bed and condenser, which ensures the stable operation of system even at relatively low exhaust temperatures. Simultaneously, the decomposition reaction increases suction pressure of compressor, so the coefficient of performance (COP) is thus greatly improved. Furthermore, the sorption bed can output cooling capacity for refrigerated compartment when the vehicle is parked. Currently, vehicle emission standards generally adopt World Harmonized Stationary Cycle test, and 13 engine operating points are selected. At an operating point 3 (a low engine load), i.e. 55% speed and 25% torque, the COP of the novel system at an evaporating temperature of −25 °C and a condensing temperature of 45 °C is 1.65, 1.5 times higher than that of conventional one. The weighted average COP under 13 operating points is still up to 1.48. Eventually, the novel system promotes the realization of low-carbon and low-cost refrigerated transportation.

Study on the effects of auxiliary condenser operation parameters on the performance of closed loop heat pump drying system

Considering the problems of high energy consumption, complex system structure and low drying temperature in current industrial drying system of metal parts, a closed loop heat pump drying system with auxiliary condenser was designed and established. The effects of auxiliary condenser operation parameters on the circulating air temperature, coefficient of performance (COP), moisture extraction rate (MER) and specific moisture extraction rate (SMER) were experimentally investigated, where the compressor rotating speed, circulating air volume, cooling water inlet temperature and flow rate respectively were 3900 r•min−1, 539.8 m3•h−1, 5∼30 °C and 30.6∼50.1 kg•h−1. The results showed that the drying temperature gradually increased with increasing cooling water inlet temperature and decreasing cooling water flow rate. When the cooling water inlet temperature and flow rate respectively were 20 °C and 34.3 kg•h−1, the drying temperature was 70.02 °C, meeting the high temperature requirement of industrial drying. Besides, the cooling water flow rate had little influence on the system COP, while the system COP increased at first and then decreased with increasing cooling water inlet temperature, reaching its maximum value 5.64 when the cooling water inlet temperature was 20 °C. Moreover, when the cooling water inlet temperatures respectively were 20 °C and 5 °C with constant cooling water flow rate 34.3 kg•h−1, the system MER and SMER could reach their maximum values of 3.8 kg•h−1 and 1.68 kg•kW−1•h−1, showing excellent dehumidification capacity. These results can provide guidance for the popularization and application of heat pump drying technology in the industrial drying.

Performance and economic evaluation of CO2 (R744) air conditioning system driven by compressed air engine

Traditional building air conditioning uses electricity or thermal energy to drive the refrigeration cycle. The energy released by the expansion of compressed air can also be used for driving the refrigeration cycle. Moreover, the expanded low-temperature air can be used in the air conditioning system too. In this paper, three forms of CO2 air conditioning systems driven by novel reciprocating piston compressed air engines were designed, namely EAGC (Exhaust Air for Gas Cooler), EAS (Exhaust Air for Sub-cooler), and EASC (Exhaust Air for Space Cooling), to analyze the performance and economics of CO2 air conditioning systems combined with compressed air energy storage technology. Twenty-seven typical cities were selected in different climate regions in China to evaluate the systems' performance and running cost under outdoor temperature changes and different electricity prices. The results show that compared with the electricity-driven CO2 air conditioning system, the three systems can greatly improve the system COP (Coefficient of Performance) but still cannot reach the performance level of the conventional freon refrigeration systems. However, in cities like Beijing and Shanghai with the large peak-to-valley electricity price difference, EASC system compared to the electricity-driven R410A air conditioning system running costs are lower, the average running cost per hour can be saved 11.96% and 16.35%, respectively. This means that the CO2 air conditioning system with compressed air energy storage technology has a certain economic application value and can be popularized on reasonable occasions. This innovative system design can help solve the contradiction between supply and demand of building energy, realize leisure energy consumption, and reduce the economic cost of energy consumption on the demand side.

A case study of a pilot system with gas-engine heat pumps and a desiccant air handling system using higher chilled water temperature in Japan

• The exhaust hot water from gas-engine heat pumps can be effectively used. • Water at 12 °C from gas-engine heat pumps achieved a 20% higher performance. • Higher chilled water temperature had no influence on the indoor environment. • Coefficient of system was 0.76 when chilled water temperature was raised. A desiccant air handling unit (DAHU) is a major dehumidification system in which adsorbents adsorb moist air. The system requires hot water to regenerate these adsorbents. In this study, a gas-engine heat pump (GHP) with a simultaneous supply of chilled and recovered hot water from the engine was installed as a heat source for a DAHU. Because a DAHU does not require low-temperature chilled water for condensation dehumidification, the impacts of higher-temperature chilled water on a DAHU and the whole system were investigated. Preliminary to the measurement, the influence of the rise of the chilled water temperature on air state after pre-cooling coil and after-cooling coil was investigated. According to this preliminary reviews, the raise of the chilled water temperature does not affect on the air state, which means there is no influence of the dehumidification amount at desiccant wheel. Furthermore, the upper limit of the chilled water temperature is at 13˚C. Field measurements with two chilled water temperatures (7 °C and 12 °C) were conducted in summer 2019. The results from these two cases showed that the rise in the chilled water temperature of the GHP improves the coefficient of performance (COP) of the GHP from 0.8 to 1.0, without any influence on the air state in the DAHU or the indoor thermal environment (temperature and relative humidity). Overall, the distribution ratio of chilled and hot water from the GHP was very small compared to that of the whole system, where the system COP was almost the same, at approximately 0.73 between the two cases. However, there is a possibility to achieve 4% of better energy performance of the system by the increase of the chilled water temperature set point from 8 °C to 12 °C.

Enhancing Electrocaloric Heat Pump Performance by Over 99% Efficient Power Converters and Offset Fields

This work analyzes how an over 99% efficient charging circuit and electrical offset fields enhance the coefficient of performance (COP) of electrocaloric heat pumps, an emerging technology with zero global warming potential. The COP is studied for Carnot-like cycles regarding the material’s permittivity and dissipation factor, and the system’s charging efficiency. Compared to the Carnot limit, a relative material COP of 50.4% is calculated for a lead magnesium niobate (PMN) ceramic, and enhanced to 87.4% by an offset field. The offset avoids high loss at low fields, where the non-linear permittivity-related dissipative loss is highest. A 99.2% efficient gallium nitride half-bridge switched-mode converter is used as charging circuit. Including the charging loss, the calculated relative system COP of 11.9% is significantly enhanced to 28.6% by an offset field. The 0.8% external loss exceeds the material loss (dissipation factor below 0.2%), reducing the system COP from the material COP. Compared to 80% efficient state-of-the-art resonant circuits for electrocalorics, this work’s approach reduced charging loss 20 times. The work contributes to transfer the high COP of electrocaloric materials also to electrocaloric heat pump systems.

A Simulation Research on NH3/CO2 Cascade Refrigeration System Based on Theoretical Model

The rapid development of the refrigeration industry has benefited production and life, and has also brought irreversible negative impacts on the current environment. Finding environment friendly, energy-saving, stable, and new-type alternative refrigerants has become a common concern and research hot spot of researchers and the refrigeration industry around the world. In this article, a NH₃/CO₂ cascade refrigeration system model is established. CO₂ is used as the refrigerant in the low temperature cycle, NH₃ is used as the refrigerant in the high temperature cycle, and the condensing evaporator is used to couple the heat exchange between the high and low temperature circuits. Based on the first law of thermodynamics and the second law of thermodynamics, the author carries out the energy analysis and exergy analysis of the cascade system. Applying MATLAB software to establish the simulation calculation of NH₃/CO₂ cascade cycle. Through simulation, the author explores the effects of low temperature cycle CO₂ evaporation temperature and high temperature cycle NH₃ condensation temperature cycle parameters on the system cycle performance and system exergy efficiency. This paper provides a certain theoretical basis for improving the design of system structure and the system performance coefficient through simulation calculation.

Energy-saving and emission reduction system of data center heat pipe based on latent heat of water evaporation

To address the current problem of high energy consumption in data centers, this paper proposes a data center heat pipe air-conditioning system based on the latent heat of water evaporation, which uses the latent heat of water evaporation for cooling by creating a low pressure environment to evaporate large amounts of water. In order to verify the effect of the system, a heat pipe test bench based on the latent heat of water evaporation was designed and built. Compared with the traditional heat pipe in the data center for heat dissipation, the performance and economy of the water evaporation latent heat pipe system designed in this paper are analyzed experimentally. A multi-physics coupled model of water evaporation latent heat pipe air-conditioning based on COMSOL Multiphysics was established to simulate and study the temperature field and velocity field distribution of water evaporation latent heat pipe air-conditioning system in data centers. The research shows that: - Under the designed test conditions, compared with the traditional heat pipe system, the water evaporation latent heat pipe air conditioner can conduct 2540 kJ more heat in one day in an outdoor environment of 24?C. - At an ambient temperature of 35?C and an indoor temperature of 25.8 ?C, the cooling capacity of the heat pipe in the data center water evaporation latent heat pipe air-conditioning system is twice the cooling capacity of the air conditioner, and the heat pipe can work efficiently regardless of the outdoor ambient temperature. - The energy-saving effect of the latent heat pipe of water evaporation in the data center has a significant effect on air conditioners with an energy efficiency rating (EER) lower than 2.5-4.4. It can improve the energy efficiency of level 5 with an EER of 2.5 to level 2 with an EER of 3.22, greatly reducing the power consumption of the data center air-conditioning system. When the EER of the air conditioner exceeds 4.4, the coefficient of performance of the data center water evaporation latent heat pipe air-conditioning system will be lower than that of the air conditioner itself.

Ohmic heating: A post production technology applied to tomato puree

In this study, ohmic heating treatment was applied to different volume by volume concentrations (100, 90, 80, 70 and 60%) of tomato puree. The puree was ohmically heated from 30 to 70°C at four different voltage gradients of 8, 6, 4 and 2V/cm for different concentrations. Measurements had been made on electrical conductivity, ohmic heating rate, pH and TSS. The voltage gradient and concentration had significant effect on electrical conductivity of tomato puree. Electrical conductivity and ohmic heating rate increased linearly with temperature, concentration and voltage gradient. The pH and TSS were also noted before and after heating. The treatment had no significant effect on pH and TSS values. With respect to system performance coefficient, as the concentration of tomato puree decreased the efficiency of ohmic heating apparatus shifted towards higher voltage gradient in the prescribed voltage range.

Study on heat transfer characteristics of indirect evaporative cooling system based on secondary side hydrophilic

Hydrophilic materials have been widely used in heat exchangers. On the Secondary side of heat exchanger, water film generated on the plate wall could affect overall heat transfer performance of the heat exchanger. In this study, an experimental analysis of two different hydrophilic materials of indirect evaporative cooler (IEC) systems was carried out. The two plate heat exchangers were finished either with TiO2 coating or a novel hydrophilic Graphene coating. First, a three-dimensional mathematical model coupled with a Volume of Fluid (VOF) model and a continuum surface force (CSF) model for heat and mass transfer of IEC was developed. The surface tension was achieved by changing the contact angle and thermal conductivity. Simulation results obtained from the developed model with and without the hydrophilic coating were in good agreement with experimental results. The deviation is within ±10% which proved the good accuracy and reliability of the model. Second, the influence of hydrophilic coating on enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP (coefficient of performance) of IEC was investigated under different boundary conditions. Compared with non-hydrophilic materials, the enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP of IEC system coated with TiO2 increased by 5.33%, 9.91%, 0.25 and 3.22, respectively. The enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP of the Graphene coated IEC system increased by 14.75%, 12.07%, 0.85 and 7.69, respectively, as compared to IEC without the hydrophilic coating. In addition, the enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP of the Graphene coated IEC system increase by 11.67%, 7.76%, 0.76 and 6.08, respectively, as compared to the TiO2 coated IEC system.

Measurement and verification of energy performance for chiller system retrofit with k nearest neighbour regression

There is no generic performance indicator for chiller systems running in different cooling load profiles. This study applies the k nearest neighbour (kNN) regression to analyse the pre- and post-energy performances of a chiller system retrofit. The system consists of five sets of chillers, pumps and cooling towers with two different capacities. The retrofit involves recommissioning the control system and replacing faulty variable speed drives. Data were logged at 15-min intervals for the evaluation of system coefficient of performance (SCOP)—the total cooling capacity divided by the total electric use of system components. A total of 15506 sets of operating conditions were gathered year-round before and after retrofit. For each post-operating condition, Euclidean distance was examined to search for five neighbours based on the system capacity, the dry bulb temperature and relative humidity of outdoor air in pre-operating conditions. The SCOP improves by 0.01–88.30% in 79.63% of the post-operating conditions when comparing with neighbour pre-operating conditions. The chiller part load ratio is ranked the first in the improvement, followed by the number of operating chillers. LOESS (local regression) curves facilitate tracking changes and boundaries of significant variables for the improvement. The carbon emissions reduce by 224386 kg CO2e after retrofit. The novelty of this study rests on aligning cooling load profiles with the kNN regression to compare directly SCOPs before and after retrofit.

Thermally regenerative electrochemical refrigerators decision-making process and multi-objective optimization

Thermally regenerative electrochemical refrigerators have drawn tremendous attention due to their reliability, quietness, eco-friendliness, non-emission of CFC gases, and potential for various applications. This work was conducted to model a thermally regenerative electrochemical refrigerator based on finite-time analysis. The proposed system is analyzed in four diverse temperature ranges, and all losses are considered for more accurate modeling by Python. Moreover, sensitivity analysis was performed for these temperature ranges. The thermodynamic analysis of these states has been demonstrated in detail for the first time. A multi-objective genetic algorithm in MATLAB software was used to achieve the maximum cooling capacity and COP and minimum input power. The optimal values, including system temperature, cell materials, and parameters related to heat exchangers and output results of the genetic algorithm, were prioritized using the weighted aggregated sum product assessment method. The results revealed that in the temperature ranges, 263K<TL<283K, 297K<TH<301K, which are the temperature ranges of cold and hot cells, respectively, the system indicated better performance. Meanwhile, selecting materials with higher specific charging/discharging capacity, isothermal coefficient, and smaller specific heat and internal resistance improves the system’s performance. The optimum values of cooling capacity and system coefficient of performance were acquired as 367.01 W and 0.7301. This paper is expected to pave the way for the lab-scale design of thermally regenerative electrochemical refrigerators.

Low-temperature air source heat pump system for heating in severely cold area: Long-term applicability evaluation

Air source heat pumps (ASHPs) have gained popularity in cold regions without central heating owing to their higher energy efficiency when compared with fossil energy sources. Although studies have shown that the short-term performance of ASHPs may meet the heating demand at an ambient temperature of −20 °C, long-term performance under actual variable meteorological conditions needs further investigation. In this study, to comprehensively evaluate the long-term performance of an ASHP system in cold climates, a three-month field test was conducted in Daqing city, which is the coldest region in China. The ambient temperature fluctuated from −24.7 °C to 15 °C during the test. The test results showed that the system coefficient of performance (COP) was related to the outdoor temperature (r = 0.8955), and when the supply water temperature increased by approximately 6 °C under an outdoor temperature of −5 ± 1 °C, the corresponding COP decreased by 14.2%. Apart from the frost temperature of −5 ± 1 °C, the relative humidity (RH) had a slight effect on the system COP. Moreover, during the three coldest days when the ambient temperature ranged from −24.7 °C to −15.0 °C, the heat produced met the heating demand, and the system ran smoothly. Compared with other common heating methods, ASHPs have the advantages of high energy conversion efficiency and low pollutant emissions. From the field test results, it can be inferred that the low-temperature ASHP system is a clean and energy-efficient heating method that is well suited for severely cold regions.

Performance analysis of a novel combined parabolic trough collector with ejector cooling system and thermoelectric generators

The paper presents a simulation for the performance analysis of integrated systems including thermoelectric generators, parabolic trough solar collectors to generate electrical power and a cooling effect. The system's thermodynamic model is solved using TRNSYS and EES software. The experiments are carried out to evaluate the performance of the parabolic trough collector for Tunisian weather conditions. Hence, the experimental data are the input for the thermodynamic model to predict the actual system's performance. The effect of the main parameters such as the collector's inlet and outlet fluid temperatures, the useful energy gain, the turbine backpressure, and the evaporator's temperature on the system's performance was estimated. The results of the mathematical model were validated by existing published results and experimental data. The results showed that the system thermal efficiency of the new system increased by an average of 60% in comparison to that of the conventional system when the evaporator's temperature increased, and 55% when the exit turbine pressure increased. The produced electrical power by the TEG module was 37.3 W for one day in summer and 28.3, 16.6, and 22.4 W in fall, winter, and spring, respectively. The system coefficient of performance was found to increase with the increase of the parabolic trough collector's area.

Thermodynamic analysis and operation optimization on a novel heating and cooling integrated system with twin screw compressor and intercooler

• A model is established for the novel heating and cooling integrated system. • There exist the optimal operating parameters to obtain the optimal COP. • The optimal COP can be identified when the heating capacity changes. • The system performance can be improved by introducing an intercooler. In response to the unreasonable utilization of energy in food processing and livestock slaughtering industries, a novel heating and cooling integrated system with twin screw compressor and intercooler is exhibited in this paper which conducts based on the conventional cascade refrigeration apparatus. The original condensation heat of refrigeration system is completely or partially recovered and the utilization of cooling and heating is achieved simultaneously. A thermodynamic model is established to determine the optimal design and operating parameters such as condensation temperatures of cycle 1 and cycle 2 ( T 1cond and T 2cond ) and compressor load rates to maximize the coefficient of performance (COP). The system performance is expected to be identified when the heating capacity and operating conditions change. The results show that T 1cond , T 2cond and compressor 3 load rate have a significant impact on the system COP with the variation of heating capacity. Finally, the system performance can be significantly improved by introducing an intercooler.