Compression Refrigeration System Research Articles

Influence of Fe2O3 and La2O3 nanoparticles on the performance of domestic refrigerator functioning with R134a refrigerant

Abstract Domestic refrigerator is working on the principle of Vapour Compression Refrigeration (VCR) system. VCR system uses compressor as one the functional member which consumes electrical energy. Due to the civilization, the usages of VCR system based equipments are increasing. Therefore, the need for electrical energy is on the rise. Therefore, the limited usage of electrical energy is desirable. Consequently, this study aimed to reduce electrical energy consumption and enhance the performance of the VCR system by using nano-refrigerants as the working medium. This research utilized two types of nano-refrigerants: R134a/Fe2O3 and R134a/La2O3.The nanoparticles concentration was varied from 0.1 g/l to 0.5 g/l and the best refrigerant was identified by comparing the performance of VCR operated with aforementioned nano-refrigerants. The properties like thermal conductivity and viscosity of nano-refrigerants were determined and compared with R134a refrigerant. Further, the power consumption, pull down time and COP of VCR system was investigated. Results revealed that the R134a/Fe2O3 and R134a/La2O3 nano-refrigerant displayed superior characteristics and showed greater performance compared to R134a refrigerant. The R134a/Fe2O3 refrigerant demonstrated a peak thermal conductivity of 0.022 W/mK when 0.5 g/l of nanoparticles were added. Further, the same refrigerant showed 27.4% decrease in electrical energy consumption compared to R134a refrigerant and showed a maximum COP of 3.5. Therefore, this study suggests that the R134a/0.5 g/l Fe2O3 could be an effective choice to lower the power consumption of the VCR system.

Low corrosive dual desiccant air conditioning: Antimicrobial activity, performance characteristics, and economic valuation with traditional VCRS

Liquid desiccant dehumidification systems (LDDS) serve as an energy-efficient alternative to conventional vapor compression refrigeration (VCR) systems, providing enhanced control over both temperature and humidity levels. However, the broader implementation of LDDS is limited due to the corrosive effects of the liquid desiccants on metal components. In response, this study introduces an economical blend of potassium formate (HCOOK) and magnesium chloride (MgCl2) designed to minimize corrosion while maintaining energy efficiency and performance. Selection of mixture ratio and solution concentration and determination of thermo-physical properties were conducted by initial lab-scale tests. Significant bactericidal effects against E. coli and S. Aureus were observed. The feasibility and effectiveness of the developed solution were experimentally tested by a comparative investigation in a large-scale solar-integrated liquid desiccant dehumidification system against standard HCOOK (63.5 wt%). The cyclic performance of the novel desiccant solution was examined under varying operational conditions for tropical climates. Results demonstrated that the corrosion levels of the new mixture are comparable to those observed with a standard 63.5 wt% HCOOK solution, while the dehumidification efficiency showed significant improvements, with moisture removal and effectiveness enhanced by 8.7–14.3 % and 5.8–15.2 %, respectively. Significant regeneration occurred between 45 °C and 55 °C. Regeneration efficiency improved by a maximum of 12.5 % relative to the standard HCOOK solution. Notably, the deployment of a solar-assisted regeneration system led to energy cost reductions by 22.8 % compared to traditional VCR systems, achieving a return on investment within 1.8 years.

Study of expansion valve capacity at constant thermal load and 5℃ room temperature in refrigerated truck unit

The main role of the expansion valve in a vapor compression refrigeration system is to regulate the mass flow rate of the refrigerant gas, so the study was conducted to evaluate the effect of variations in the expansion valve capacity on the cooling performance of the Truck Refrigerator unit. This is related to the suitability of the temperature of the products transported using the truck refrigerator, which often experiences damage so that the product or goods are rejected in the market. The study showed that the cold reach time to obtain a temperature of 5oC in the refrigerator truck cooling room when using an expansion valve with a larger cooling capacity (3500) occurred faster than an expansion valve with a standard cooling capacity (2000 W). The Coefficient of Performance (COP) that occurred when using an expansion valve with a standard cooling capacity (2000 W) was 3.099. This value is smaller than the expansion valves with a cooling capacity of 1000 W and 3500 W with values ​​of 3.226 and 3.928, respectively. Using an expansion valve with a cooling capacity that is more significant than the standard was found to produce the highest COP. This also means lower power consumption and, of course, lower electricity bills. The work of the compressor in the refrigeration system is very dependent on the COP value.

Energy, exergy, environmental, and enviroeconomic (4E) analysis of cascade vapor compression refrigeration systems using nanorefrigerants

The refrigerants used in traditional vapor compression refrigeration systems are harmful to the ozone layer and contribute to global warming. The demand for refrigeration is increasing because of global warming. In this study, for the first time, an energy, exergy, environmental, and enviroeconomic (4E) analysis was performed using different refrigerants and nanoparticles to reduce the energy required in low-temperature vapor compression cascade refrigeration systems and to determine more environmentally friendly nanorefrigerants. The R290 refrigerant was used for the Low-Temperature Circuit (LTC), while the High-Temperature Circuit (HTC) used RE170, R1234yf, R600, R600a, and R450A refrigerants. The nanoparticles used in the analysis were Al2O3, CNT, CuO, TiO2, ZnO, and SiO2. The R600 nanorefrigerant performed the best, whereas the R1234yf nanorefrigerant performed the worst. The results indicate that the CuO nanoparticles provided the highest performance. In addition, the results showed that the R290+R600-CuO nanorefrigerant emitted 11 % less CO2 than the pure R290+R600 refrigerant. The nanorefrigerants provide a more environmentally sustainable option because of their high efficiency and lower energy consumption than conventional refrigerants.

Dispersion and Stability Behaviour of Graphene and MWCNT Based Nano-Lubricant for Vapour Compression Refrigeration (VCR) System

Incorporating nanoparticles into oil compressors marks a significant advancement in scientific research. It has been widely demonstrated that the inclusion of nanoparticles can markedly improve the system's efficiency by reducing energy consumption, decreasing evaporator temperatures, and increasing condenser temperatures. Nanoparticles made of carbon, including those of metal, metal oxide, and metal hybrids, are particularly valued for their superior properties and are deemed to have considerable potential for achievements. This study focuses on examining the stability of graphene and multi-walled carbon nanotubes (MWCNT) in polyolester (POE) oil as a precursor to replacing conventional lubricating oil in refrigeration systems separately. Graphene nano-lubricants were tested at concentrations ranging from 0.1 to 0.3 g/L with the selected surfactant, cetyltrimethylammonium bromide (CTAB), in a 1:1 ratio, while MWCNT nano-lubricants were tested from 0.5 to 0.7 g/L. All samples were prepared using a two-step method that involved magnetic stirring at 1250 rpm for 45 minutes, followed by ultrasonication for 30 minutes. The samples underwent evaluation through three methods of observation. Initial visual observation was conducted immediately after production, then after a 24-hour settling period, and finally, after seven days, the three most optimal samples were identified. For MWCNT, an additional stability test was necessitated due to the high concentration levels, making it challenging to determine the three most stable concentrations. The UV-VIS spectrophotometer played a crucial role in analyzing the stability of the samples, providing data that enabled more precise results. The absorption peak at a wavelength of 294 nm reached its highest absorption value of 0.892 (a.u.) at a concentration of 0.2 g/L. In the case of MWCNT, after testing all samples, concentrations of 0.5, 0.55, and 0.65 g/L were identified as the best options based on peak absorption at different wavelengths, with their peaks at 4.87, 4.045, and 4.116 (a.u.), respectively. The Zeta Potential Analyzer confirmed the stability of these concentrations, indicating a moderate stability with values around -37.4 mV. This level of stability was also observed in MWCNT samples, with the three chosen concentrations showing excellent stability at 88.4, -84.9, and -137 mV, respectively. Among all tested nano-lubricant samples, those with concentrations of 0.2 g/L and 0.65 g/L for Graphene/CTAB/POE and MWCNT/POE, respectively, demonstrated the highest stability and optimum performance. This suggests that these concentrations have the potential to serve as replacements for POE oil in refrigeration systems.

Thermodynamic assessment and optimization of a solar and diesel engine exhaust-driven ORC-VCR system

Waste heat recovery is characterized as an appealing method to enhance overall energy efficiency. Therefore, in this paper, the Vapor Compression Refrigeration (VCR) system employs the diesel engine exhaust-powered Organic Rankine cycle (ORC) to generate the cooling effect. The ORC is further modified in order to generate additional power using solar energy. The source temperatures of diesel engine exhaust and solar heat are taken in the range of 690-810 K and 433-473 K, respectively. The thermodynamic investigation consists of an energy and exergy analysis to determine the effect of turbine inlet temperatures, condenser temperature, and evaporator temperature over the performance parameters of the ORC-VCR system. The study exhibits the coefficient of performance (COP) of the system for the Benzene-R601 refrigerant pair is maximum which is 1.18. The exergetic efficiency for the same refrigerant pair is 18% more as compared to Cyclohexane-R1234yf refrigerant pair. A multi-objective optimization procedure was executed utilizing a genetic algorithm (GA), which suggested that at the temperature of the higher-pressure turbine is 548.33 K and the temperature of the lower-pressure turbine is 439.19 K, which delivered the maximum cooling effect i.e. of 33.72 TR. Moreover, the system exhibits better COP and cooling capacity at lower ambient temperatures.

Comparative thermodynamic study of CO2 transcritical supermarket booster refrigeration system combined with vapor injection and parallel compressionÉtude thermodynamique Comparative du système de réfrigération transcritique de supermarché au CO2 combiné à l'injection de vapeur et à la compression parallèle

The use of CO2 refrigerants in supermarket refrigeration has recently demonstrated great potential owing to their excellent thermophysical properties and environmental protection. To further improve the efficiency of transcritical CO2 refrigeration systems, a parallel compression cycle with vapor injection system (SRC) is proposed. Thermodynamic model is established to investigate the influence of working condition parameters and compared with basic booster refrigeration system (BRC) and parallel compression refrigeration system (PRC). In addition, the effect of vapor injection parameters on the characteristics of the proposed system is investigated. The results show that the medium pressure has little effect on BRC, while the optimum value exists for both PRC and SRC. The performance of the three systems can be significantly enhanced by optimizing the discharge pressure and medium pressure. The optimal value of the relative vapor injection pressure is constant at about 1.15. The maximum coefficient of performance (COPmax) of the SRC is significantly improved by 23.99%∼32.14% and 14.44%∼20.07% at disccussed working conditions compared with BRC and PRC, respectively. In summary, this paper confirms the performance enhancement potential of the proposed cycle and provides theoretical support for its practical implementation.

Experimental assessment of using phase change materials in vapor compression refrigeration systems for condenser pre-cooling

The primary objective of this investigation is to empirically assess a new vapor compression cycle while employing phase change material (PCM) energy storage. During off-peak periods, the PCM undergoes charging, and during on-peak hours, it is discharged to cool the refrigerant entering the condenser, thereby enhancing the condenser's overall performance. In contrast to previous studies that exclusively examined the charging or discharging processes of air conditioning (AC) units, this research delves into the entire 24-h charge and discharge cycle. The proposed system is subjected to testing under identical conditions, both without PCM (conventional mode) and with a PCM storage tank, throughout a 24-h period. The PCM storage tank, which utilizes water as its phase change medium, possesses a volume of approximately 300 L and starts at an initial temperature of 25 °C. The outcomes of the study demonstrate notable improvements when incorporating the PCM storage tank. Specifically, the daily coefficient of performance (COP) increases by approximately 7 %, rising from 2.17 to 2.33. Additionally, it leads to a reduction in both the daily available cooling load and daily compressor energy consumption, with decreases of approximately 3.7 % (from 58.4 to 56.2 kWh) and 10.3 % (from 26.9 to 24.1 kWh), respectively.

Designing and multi-objective optimization of a novel multigenerational system based on a geothermal energy resource from the perspective of 4E analysis

Over the past few years, a growing emphasis has been placed on providing sustainable energies to reduce carbon emissions and promote energy efficiency. This paper delved into energy, exergy, exergoeconomic, and exergoenvironmental investigation for a system that combines the Kalina cycle, a double-effect absorption chiller with a vapor compression refrigeration system coupled with an air handling unit driven by a geothermal renewable energy resource. This innovative system generated four distinct outputs: electricity, potable water, cooling load, and hot water. Key system performance variables, such as net power output, coefficient of performance, sum unit cost of the product, energy and exergy efficiencies, the temperature of supply air to the cold store, and potable water production in the base mode, are measured at 63.45 kW, 0.83, 56.74 $/GJ, 62.28 %, 45.67 %, 268.7 K and 20.82 lit/h, respectively. This research explored the impact of various parameters on the output variables, the exergy destruction and environmental impact rate of all components, and the net percent value of the proposed system. The multi-objective optimization significantly improved energy and exergy efficiencies by 6.83 % and 1.8 % from its base mode. Exergy and exergoenvironmental analysis revealed that the highest exergy destruction occurs in Re-injection, and the highest environmental impact rate associated with exergy belongs to the HPG component. Moreover, the geothermal section has the largest share of exergy destruction, approximately 58.5 % of the total exergy destruction of the system.

Experimental performance investigation on a desiccant-assisted two-stage evaporative cooling system in hot and humid areas

The escalating demand for energy-efficient and eco-friendly air conditioning systems in buildings has spurred the development of comfortable, efficient, and cost-effective air handling system configurations. Desiccant cooling has shown a higher coefficient of performance (COP) compared to traditional vapor compression refrigeration (MVCR) systems. However, current desiccant cooling facilities struggle to decouple and efficiently handle indoor heat and moisture loads. The complexity of these facilities has kept intricate cooling systems remaining theoretical, requiring simplification and experimental investigation. This paper presents an experimental study on a compact, two-stage evaporative cooling system assisted by a liquid desiccant. A key innovation of this system is the inclusion of a two-stage heat exchanger that adeptly manages the decoupling of indoor heat and moisture loads under challenging high-temperature and high-humidity conditions. Performance analysis was conducted experimentally under three hot and humid climatic conditions using an optimized operating parameter scheme. Starting from an initial condition of 36.22 °C and a humidity ratio of 0.028 kg/kg, the proposed system achieves COP values ranging from 11.3 to 18.4 without compromising indoor comfort or facility compactness. Under high heat and high humidity conditions, the optimized system extracts 20 % of the product air as the secondary air source. It can reach a minimum supply air temperature of 18.44 °C, achieved under optimized conditions of low wind speed (1.0 m/s), high desiccant concentration (35 %), and substantial desiccant flow (0.09 kg/s). Experimental studies of this new system provide the possibility of achieving high efficiency in air handling over a wide range of temperatures and humidity.

Performance evaluation of a hybrid photovoltaic-vapor compression system serving a refrigerated van

The refrigerated transportation industry's growth necessitates addressing energy consumption and greenhouse gas emissions. This study estimates a photovoltaic system's energy and environmental benefits to power a vapour compression refrigeration (VCR) system serving a light-duty commercial refrigerated van. A comprehensive energy model encompassing thermal, electrical, and battery sub-models simulating the system's dynamic behaviour is calibrated with real-world data referring to an urban single-delivery mission. The potential benefits are estimated for a long-distance single-delivery mission starting from the University of Salerno (Italy) and ending at the Jaume I University in Castellon de la Plana (Spain). The results have shown that the system can reduce fuel consumption for refrigeration by more than 88 % during summer months and allows neutral refrigeration during winter months, leading to on-wheel emission savings between 4 and 8 gCO2,e/km. When considering total emissions, including electrical energy from the power grid and the increased weight due to the PV system, a 33–47 % reduction is obtained, corresponding to 1–5 gCO2,e/km. In detail, PV panels can cover up to 19 % of the total energy requirements. In economic terms, the system allows a cost-saving between 0.1 and 0.3 c€/km. The low complexity and promising results suggest the hybrid PV solution is a viable path towards decarbonising refrigerated transport.

Adaptive control for refrigeration via online identification

Vapor compression refrigeration systems (VCRS) occupy a crucial position in modern society and in the field of thermal sciences. However, the operation of VCRS is subjected to both external disturbances (dynamic-changing environment) and inherent system characteristics (coupling or nonlinear features), leading to issues like reduced refrigeration efficiency and significant fluctuations in cooling capacity. To address these challenges and enhance the adaptability of VCRS in dynamically changing environments, this study establishes a dynamic simulation model for VCRS based on the Switched Moving-Boundary method. The impact of external environmental disturbances on refrigeration performance is investigated, and continuous online identification methods are employed to elucidate its internal coupling characteristics and nonlinear features. The adaptive temperature control method is introduced, benefiting from the developed recursive least squares method with a forgetting factor for online identification, achieving precise model identification which facilities the real-time parameters tuning of adaptive controller. The results indicate that the hybrid paradigm of online identification and adaptive control algorithm not only effectively handles various disturbances but also reduces overshoot and IAE by 2–3 orders of magnitude compared to traditional PID controllers. Adaptive PID control maintains overshoot in the 10–4 order of magnitude and IAE in the 10–5 order of magnitude.

Energy and exergy analysis of a two-stage cascade vapor compression refrigeration system with modified system configuration

This study proposes a modification to the two-stage cascade vapor compression refrigeration system by adding internal heat exchangers that function as subcoolers and desuperheater. The influence of each internal heat exchanger proposed on the exergy destruction rate, exergy efficiency, compressor power consumption, ECOP, and COP of the system was investigated. Additionally, various refrigerant combinations were considered as working fluids to evaluate which combination is the most suitable for the proposed system. Mathematical models based on the principles of thermodynamics were established in Engineering Equation Solver (EES), a software used for energy and exergy analysis. The results reveal that the addition of specific internal heat exchangers causes either an increase or decrease in overall system performance, depending on the type of refrigerant combination used. Consequently, there exists an optimal system configuration for each refrigerant combination. Compared with the conventional two-stage cascade refrigeration system, the optimal system configurations in the present study exhibited higher overall system performance. A maximum increase in exergy efficiency, ECOP, and COP of 7.31 %, 9.8 %, and 7.3 %, respectively, can be observed with the refrigerant combination R450A/R404A. Additionally, the results of the exergy analysis identify that the HTC compressor, condenser, LTC compressor, and cascade condenser are the primary contributors to the exergy destruction rate within the system.

Performance of R134a vapour compression refrigeration system by using Gr and Al2o3 hybrid nano lubricants

Nowadays, in many developing countries like India they are facing the shortage of energy. The Refrigeration system has become the major consumer of energy for many industrial as well as household applications. So, it is the need to enhance the energy efficiency of the refrigeration systems. Performance of the refrigeration system can be improved either by increasing the rate of heat absorption in evaporator or by reducing the compressor power. Use of efficient lubricant oil can help to remove the heat generated in the compression process which leads to less power consumption. Development in Nanotechnology makes it possible to develop a new class of lubricant called nanolubricant, in which nanoparticles are added in base lubricant oil to enhance the thermal properties. The two step technique with ultrasonic agitation force is used tosynthesise stable nanolubricant. The present study investigates the performance of an R-134a refrigerant vapour compression refrigeration system using nanolubricant with different volume concentrations (0.05%, 0.075%, 0.1% and 0.2%) of Graphene/Aluminium nanoparticles to mineral oil (MO) experimentally. The result shows maximum enhancement in COP approximately as 85% for 0.075 % volume fraction Nano lubricant as compared to base fluid. Use of nanolubricant saves approximately 27% compressor power.

Thermal Performance of Vapour Compression Refrigeration System using Bimetallic Strontium Hexaluminate Nanorefrigerants

Nanoparticles are added to standard compressor lubricants to improve performance and reduce the energy consumption of vapour compression refrigeration systems (VCRS). This work evaluated the compatibility, viability, and utility of a bimetallic oxide strontium hexaluminate (SrAl12O19) nano-lubricant with nominal sizes of 20–40 nm by characterising and evaluating its thermophysical properties while assessing its effect on the performance and energy consumption of existing, unmodified VCRS. Eco-friendly R600a were used as the system's refrigerant and the performance, energy consumption, and energy efficiency of VCRS were investigated by altering the concentration of SrAl12O19 (1%–20%) in the compressor lubricant. The results showed that as the temperature increases, the viscosities significantly decreased and increased as the concentration of nanoparticles is increased. In contrast, the density and acidity of the nanolubricant increased as the volume concentration of nanoparticles increased. The addition of nanoparticles into the compressor oil enhanced the performance of the VCRS performance and reduced the energy required to operate the system; however, these performance metrics decreased as the concentration of nanoparticles increased further. When the concentration of nanoparticles increased, exergy efficiency reached the maximum at 5% volume concentration.

Economic and technical optimization of a tri-generation setup integrating a partial evaporation Rankine cycle with an ejector-based refrigeration system using different solar collectors

Three collector types, namely parabolic trough solar collector (PTSC), linear Fresnel collector (LFC), and dish collector, are employed to drive a tri-generation configuration composed of a partial evaporation Rankine cycle (PERC), a hot water production unit (HWPU), and a cascade ejector-based compression refrigeration system (ECRS) for electricity, cooling, and heating production. The ECRS is integrated with the topping PERC through an absorption refrigeration system (ARS). Moreover, the collector is indirectly connected to the system by a storage tank to increase the operating hours of the system. The performance of the system is evaluated by thermodynamic and economic analysis. The three-objective optimization result is a testament to the fact that utilizing PTSC brings about the best performance of the system. The system exergy efficiency (ηex) in the case of PTSC is 8.1 % and 24.9 % higher than in the case of LFC and dish collector, respectively. The economic performance of the system in the case of PTSC is superior to that of the dish collector. Furthermore, the PTSC case results in a relatively similar economic performance to the LFC case. The system produces power, cooling, and heating at rates of 200.8 kW, 564.9 kW, and 795.7 kW in the optimum case of utilizing PTSC, respectively. Moreover, ηex, total cost rate (C˙tot), and specific cost of tri-generation (ctri) are obtained as 11.48 %, 204.7 $h−1, and 44.91 $GJ−1, correspondingly. The results indicate that ηex of the proposed layout in the case of PTSC is superior to a comparable tri-generation configuration introduced in the field by 2.78 % points.

Selection of refrigerant based on multi-objective decision analysis for different waste heat recovery schemes

Waste heat generation, upgrading, and refrigeration are the fundamental ways to recover and utilize waste heat. The rationalizing the use of refrigerants also contribute in creating energy savings and minimizing carbon emissions. This study evaluated the thermodynamics, economics, and environmental of different types of refrigerants in three kinds of waste heat recovery schemes: generate electricity, heat pump, and refrigeration. Based on this, the entropy weight and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) were combined to assess the overall performance of the refrigerants. A thorough analysis revealed that R1234ze(E) can replace R245fa and R123 in the organic rankine cycle (ORC). The best refrigerant for vapor compression refrigeration (VCR) and high temperature heat pump (HTHP) systems is R1243zf. In addition, the multi-objective decision analysis shows that the performance difference among the nine selected refrigerants is the total cost, followed by the environmental impact. The approach is successful in recognizing the variations between different refrigerants in the same waste heat recovery scheme and gives a thorough evaluation. It sets instructions for the future use of eco-friendly refrigerants and their application waste heat recovery schemes.

Unsteady-state entropy generation analysis of the counter-flow dew-point evaporative coolers

The surging demand for air conditioning, especially in hot climates, underscores the urgency of strategies aimed at curbing fossil fuel reliance and fostering energy saving strategy. Despite the longstanding utility and advantages of the conventional mechanical vapor compression refrigeration system, sustainability hurdles persist owing to its pronounced electricity demand. While evaporative cooling, harnessing water evaporation, emerges as a more efficient alternative, its efficacy is contingent upon environmental conditions. Addressing this, dew-point evaporative cooling (DPEC) presents an innovative direction, showcasing superior efficiency by directing supply air into a wet channel. This study delves into the thermodynamic losses within a counter-flow configured DPEC system, employing a transient entropy generation model rooted in the second law of thermodynamics to provide a comprehensive analysis of DPEC’s performance. Key findings that emerged from this study reveal that (1) the transient entropy generation is intricately distributed across different layers of the dew point evaporative cooling (DPEC) system, including dry air, wet air, the channel plate, and the water film; (2) Parametric analyses highlight the significant impact of factors on entropy generation, inlet air temperature has a minimal effect on system efficiency, but higher temperatures increase thermal losses. Excessive humidity limits evaporative potential, while low humidity significantly increases entropy generation. The system performs optimally at a working ratio of 0.3 and lower air velocities (within the inlet air velocity range of 0.6 to 2.2 m/s). Channel length has little impact, while the system is more sensitive to channel height, with a height of 2.5–3.5 mm being conducive to better performance. Experimental validation demonstrates the model’s accuracy in predicting system performance. The research contributes to a deeper understanding of DPEC systems, offering insights for achieving optimal operating conditions and enhancing overall efficiency in the pursuit of sustainable development.

Energy, exergy, environment and economic (4E) analysis of PV/T module assisted vapor compression refrigeration system: An experimental study

Despite the rise in the prices of fossil fuels, the increase in their demand, and damaging the environment, a large part of the world's energy needs have been today met by fossil fuels. In this direction, interest in renewable energy sources has increased. Solar energy stands out among renewable energy sources because it is endless and clean. However, today, the use of solar energy is not used alone, but in combination with other thermal energy systems. In building applications, it is mostly used in heating, refrigeration, and HVAC systems, which have a high part in energy consumption. In this study, the solar energy and cooling system were not used separately as in previous studies but were used as a hybrid. The focus was on increasing the performance of both systems by operating them together. In this study, energy, exergy, thermoeconomic, and environmental analyses were applied to the PV/T-assisted vapor compression refrigeration system (PV/T-VCRS) at different storage temperatures (25 °C, 30 °C, and 35 °C). As a result, an 8.5 % lower surface temperature of the module in PV/T-VCRS 25 °C was measured compared to PV/T-VCRS 30 °C and 35 °C. In direct proportion to the module surface temperatures, 13 % better electrical efficiency was obtained in PV/T-VCRS 25 °C compared to 30 °C and 35 °C. The COP value increased by 15.46 % in PV/T-VCRS 25 °C compared to 30 °C and 35 °C. A 13 % improvement in exergy efficiency was observed in PV/T-VCRS 25 °C compared to 30 °C and 35 °C. The enviroeconomic parameter PV/T-VCRS is calculated as 15.17 ¢/h, 16.52 ¢/h, and 17.6 ¢/h for 25 °C, 30 °C and 35 °C. Another advantage of the system is that hot water is obtained at set temperatures. In PV/T-VCRS, 475 L, 300 L, and 210 L of hot water were obtained at 25 °C, 30 °C, and 35 °C, respectively. As a result, the performance of the PV/T-VCRS was good, with the added benefit of performing close to the performances when PV/T and VCRS were used separately.

Parametric Based Techno‐Economic Evaluation for a Solar Thermal‐PV Integrated Multi‐Commodity Storage Facility

ABSTRACTPostharvest losses and spoilage of agricultural products are a major problem for tropical countries, and it is even more challenging for countries encountering fluctuating power shortages, such as Pakistan. Therefore, this study focused on the energy and economic analysis of cold storage to store three products (potatoes, pomegranates, and potatoes) according to the season and storage span throughout the year. The cooling load of the cold store was supported by a LiBr‐H2O vapor absorption and vapor compression refrigeration system to maintain the desired temperature for each product during cold storage. A solar thermal PV system is installed to operate cold storage refrigeration systems. Cold storage performance was analyzed by developing thermal models of integrated systems using the ambient conditions of Lahore, Pakistan. A parametric study was also conducted to analyze the impact of various working parameters on integrated system performance, and it was found that the maximum peak cooling load of 91 kW inside cold storage is attributed to pomegranates owing to high ambient conditions during its loading month. The product loading rate significantly affects the cooling load of cold storage and varies directly with it, as observed for an increase in the product loading rate from 0 to 50 000 kg/day cooling load also increases from 34 to 87 kW. To meet the thermal demand of the generator of the vapor absorption system, parabolic troughs were installed to operate cold storage, and it was found that a minimum of four PTC were needed to support the peak cooling load at the maximum product loading rate and minimum DNI value. To meet the electrical demand of cold storage electrical equipment and the compressor of the vapor compression system, solar photovoltaic panels were installed, and it was found that a minimum of 618 panels was required at a minimum tilted radiation value. To validate the viability of proposed design system economic analysis was also conducted which revealed a payback period of 12 years for Kinnow and potatoes and 16 years for pomegranates.