Compression Refrigeration System Research Articles

Performance Evaluation of Water Cooled Condenser of Air Conditioner Working on VCRS

VCRS commonly known as (Vapour Compression Refrigeration System) is widely adopted method for air conditioning of buildings, in pharmaceutical industry for storage of medicine, in hospitals, automobiles etc. There are several methods for increasing the efficiency% (COP) of an VCRS cycle. Some of the modification can be done in Compressor, Condenser, Evaporator, and in Refrigerant . In this experiment, we adopted method of Subcooling to reduce Compressor work. This study investigates the implementation of subcooling in the condenser of a Vapour Compression Refrigeration System (VCRS) to enhance its efficiency and reduce power consumption. The traditional condenser design is modified by submerging it in a water tank, allowing for subcooling of the refrigerant. The subcooling process involves lowering the temperature of the refrigerant below its saturation temperature, which improves the system’s Coefficient of Performance (COP) by increasing the density of the refrigerant entering the expansion valve. This modification aims to optimize the heat rejection process and enhance the overall performance of the refrigeration system .Experimental result demonstrate a significant reduction in power consumption and an improvement in COP, highlighting the effectiveness of the condenser subcooling method in enhancing the efficiency of VCRS. Keywords : Compressor, Condenser, Expansion Valve, Evaporator.

Assessment of using different ozone-friendly R22 alternative refrigerants in residential air conditioners in a high-ambient temperature country

The performance of a vapor compression refrigeration system (VCRS)-based residential air conditioner operating in a high-ambient temperature (HAT) country was investigated using six zero-ODP (ozone depletion potential) refrigerants as replacements to R22. The non-flammable alternative refrigerants considered in the present research were R134a, R404A, R407C, R410A, R448A, and R507A. Using the basic conservation laws, the VCRS was modeled during steady-state operation and solved using engineering equation solver (EES) software. Coefficient of performance (COP), pressures and temperatures at compressor suction and discharge, Global Warming Potential (GWP), critical pressure and temperature, compressor pressure ratio, volumetric cooling capacity (VCC) specific cooling capacity (SCC), and refrigeration effect were utilized as assessment criteria for the alternative refrigerants considered. From these refrigerants, the highest values of suction pressure, discharge temperature, and condenser pressure were attained by R410A. In addition, the discharge temperatures for all refrigerants, except R134a, were all higher than their corresponding critical values, causing a quicker drop in the VCRS’s performance. As an alternative refrigerant, R407C showed the highest SCC of 141.0 kJ/kg followed directly by 139.2 and 138.0 kJ/kg for R410A and R448A, respectively. A reverse trend was found for VCC with respective values of 4722 and 3775 kJ/m3 for R410A and R448A. Lower volume flow rates and smaller-sized compressors are expected for higher VCC refrigerants. The same trend was found for the compressor’s specific work input and condenser’s specific heat transfer with values of (51.14, 46.82, and 45.38 kJ/kg) and (190.3, 187.8, and 183.4 kJ/kg) for R410A, R407C, and R448A, respectively. For applications in HAT countries, larger condenser’s specific heat transfer makes the refrigerant more applicable. Conversely, with respect to COP, refrigerant R134a with a value of 3.075 was the superior alternative followed by R448A and R407C with respective COPs of 3.042 and 3.011. Based on the overall assessment in terms of environmental obligation, COP, compressor input power, refrigerant flow rate required, and all the evaluations made in this research, refrigerant R448A was recommended as the most appropriate substitute to R22 which can effectively be used in residential air conditioners in a HAT country.

Integrated Approach for Enhancement of Vapor Compression Refrigeration Systems with Spiral Condenser Retrofitting and Refrigerant Blend Compatibility

An integrated approach for enhancing Vapor Compression Refrigeration Systems (VCRS) through Spiral Condenser retrofitting and compatibility with refrigerant blends is proposed in this paper. The objectives include the design and development of an experimental setup compatible with refrigerant blends, experimentation and analysis of results for retrofitting the setup with a Spiral Condenser, validation of experimental results, and determination of system energy effectiveness and payback period. The methodology involves systematic design, experimentation, validation, and analysis, culminating in insights into VCRS enhancement strategies. The findings contribute to advancing VCRS technology, optimizing performance, and promoting sustainability in refrigeration systems.

An examination of the vapour compression refrigeration system performance utilizing several environmentally friendly refrigerants and the effect of nanoparticles- a review

The refrigeration system stands out as a significant contributor to the escalating trend in energy consumption. Therefore, implementing energy-saving measures is considered one of the most effective strategies for addressing this challenge. Nanofluids demonstrate remarkable promise in enhancing refrigeration systems' thermodynamic and mechanical efficiency. In contemporary times, there is a global emphasis on exploring nano refrigerants to enhance the heat transfer properties of cooling systems. Household and industrial refrigeration systems commonly utilize Hydrofluorocarbons (HFCs) because of their exceptional thermodynamic attributes. Nevertheless, the Kyoto Protocol has classified HFCs as contributors to global warming because of their high (GWP) value, which stands at 1300., their improved Coefficient of Performance (COP), and, critically, a lower GWP while having zero Ozone Depletion Potential (ODP). Integrating nanoparticles with high thermal conductivity into traditional refrigerants has revealed compelling outcomes. These include heightened heat transfer coefficients, enhanced (COP), and reduced energy consumption by compressors in household refrigerators. This article explores the use of environmentally friendly refrigerants and the impact of nanoparticles on refrigeration systems.

Experimental investigation on the influence of electronic expansion valve opening on the performance of miniature refrigeration system

In the cooling of personnel and electronic equipment under specific conditions, the miniature refrigeration system needs to provide different cooling capacity to adapt to different working conditions. At present, most scholars use capillaries as throttling components. Compared with capillaries, miniature refrigeration systems using electronic expansion valves as throttling components can provide a wider range of cooling capacity adjustment. Therefore, this study constructed a miniature vapor compression refrigeration system based on electronic expansion valves as throttling devices, with a system weight of 3.0 kg and dimensions of 380 mm × 300 mm × 200 mm. The experiment investigated the impact of electronic expansion valve opening on compressor power, cooling capacity, and COP under different refrigerant charge conditions. Results indicated that at an electronic expansion valve opening of 90, within the experimental range, there was a relative change in cooling capacity of 39.85 % and a relative change in COP of 29.11 % as the refrigerant charge increased. Refrigerant charge had a significant effect on the cooling capacity and COP of the miniature refrigeration system. Under the optimal refrigerant charge of 70 g, within the experimental range, there was a relative change in cooling capacity of 88.14 % with varying electronic expansion valve opening. The use of electronic expansion valves as throttle components in miniature refrigeration systems allows for a wider range of cooling capacity adjustments, making them suitable for more cooling conditions.

Energy, environmental and economic analysis of low GWP refrigerant heat pumps for simultaneous heating and cooling applications

Industries such as hotels, pharmaceuticals, dairy and food and beverage units require heating and cooling for their functional requirements. These industries mostly use fossil fuel-fired boilers for heating (hot water at 60 to 90 °C) and vapor compression refrigeration systems for cooling (−30 to 5 °C), which results in higher primary energy consumption and CO2 emissions. Heat pumps (HPs) are a sustainable option for meeting the simultaneous heating and cooling demands. However, HPs use synthetic refrigerants with high global warming potential (GWP). Therefore, this research aims to evaluate the potential of low and medium-temperature HPs using low GWP refrigerants such as R744, R290, R600a, R161, R1234yf, R1234ze(E) and R1233zd(E). The best refrigerant for the HPs is proposed based on energy efficiency, environmental impact and economic feasibility as critical factors, compared with the conventional high GWP refrigerant (R134a). The occurrence of pinch points across the gas cooler/condenser is evaluated in the analysis. Life cycle climate performance (LCCP) is assessed to study the environmental impact. Also, the operating costs of these HPs are estimated and compared with the conventional systems used in the industry. Results show that R744 HP is an energy-efficient and clean solution for simultaneous heating and cooling applications, primarily at higher temperature lift (lower Tw,i and higher Tw,o) conditions.

Performance Enhancement Analysis of Environmentally Friendly Refrigerants

Due to the impact of global warming and climate change, more and more people are starting to have a clearer understanding and vigilance about greenhouse gases. To prevent further deterioration of the global environment, this study examines the coefficients of performance of 21 currently available refrigerants with very low global-warming potential and zero ozone-depleting potential under evaporation temperatures of 10, −20, −40, and −60 °C and condensation temperatures of 30, 40, and 50 °C, respectively. It is found that the use of pure refrigerant in a two-stage refrigeration system to replace the single-stage refrigeration system, in addition to mixing it into an appropriate mixture, can effectively improve the performance coefficient of the refrigeration system. For single-stage vapor compression refrigeration systems, R1234ze(Z), R601, and R1233zd(E) have the best refrigeration performances among the environmentally friendly refrigerants studied, while R441A performs the worst for Teva = 10 °C and −20 °C. Moreover, RE170 has the highest COP of the refrigeration system for Teva = −40 °C and −60 °C. However, R1234yf performs worse in COP when the evaporation temperature is lower, and it ranks last for Teva = −60 °C. When a double-stage vapor compression refrigeration system is employed instead, the percentage increase in the COP of the system using R1234yf becomes the largest for Teva = −40 °C and −60 °C. However, the growth rate of R717 ranks last for Teva = −60 °C. For an R717/R1234yf mixture at an optimum mass fraction of 0.25, the COP of the refrigeration system can be increased up to 25.8% despite an increase of 15.2% in operating pressure compared to R1234yf. The discharge temperature may rise; however, there will be no overheating problem for the compressor.

Performance evaluation of VCR system with pure and various blends of R134a, R1234yf, and R1234ze (E) refrigerants

AbstractThe current small passenger car vapor compression refrigeration systems use high global warming potential (GWP) refrigerants causing the greenhouse gas effect. In the present work, the low GWP of two pure refrigerants, R1234yf and R1234ze (E), and 16 blends of R134a, R1234yf, and R1234ze (E) are analyzed numerically. The experiments were conducted with R134a refrigerant to validate the numerical results. The experiments were conducted at the compressor speed of 600–1500 rpm and the condensing air at 30–40°C, relative humidity of 85%, and velocity of 1–3 m/s. The simulation and experimental results for R134a are deviated by a minimum of 10% and a maximum of 15%. It is found that the latent heat of vaporization of the two refrigerant mixtures with 80% R134a–20% R1234yf and the three refrigerant blends of 50% R134a–10% R1234yf–40% R1234ze (E) are the highest among 16 combinations. The other blends show a moderate difference of latent heat with R134a, but for maximum cooling capacity, the blends with 80% R134a–20% R1234yf and 50% R134a–10% R1234yf–40% R1234ze (E) are found to be more suitable for practical applications.

Impact of heat infiltration on the cooling capacity evaluation of an evaporator for household refrigerator-freezers with a non-adiabatic capillary tube

This study experimentally evaluates the cooling capacity of an evaporator in household refrigerator-freezers, typically scaled in hundreds of Watts, and investigates the impact of heat infiltration from the environment. Despite the scarcity of both quantitative and qualitative research in this area, this study provides data from a lab-scaled vapor compression refrigeration system that mimics a real-world side-by-side refrigerator-freezer. Experiments were conducted under conditions reflecting the household refrigerator-freezer, yielding 74 data points under quasi-steady state conditions. Despite careful insulation, heat infiltration from the ambient to the refrigerant flow in the evaporator occurred due to the significant temperature differential, impacting the cooling capacity evaluation fatally with a heat balance error of 26%. However, when considering the effects of heat infiltration, the error in the evaporator heat balance dropped to 6% significantly. The findings highlight the sensitivity of evaporator’s cooling capacity, less than 300 W, to external thermal factors during empirical evaluation. This study underscores the challenges of heat infiltration and the importance of considering such factors when assessing evaporator cooling capacity. The provided comprehensive analyses significantly contribute to the experimental prototyping of evaporators, emphasizing the need to account for external thermal influences during the evaluation process.

Refrigerants for eutectic refrigerating systems–Experimental results and future consideration

The new European F-Gas and PFAS Directives threaten to dramatically reduce quotas or even outright ban synthetic refrigerants, and transition to natural refrigerants in the near future seems inevitable. This article examines eutectic refrigerating systems used in low-temperature transport refrigerators for retail distribution considering transition to natural refrigerants. The main limitation for the operation of eutectic systems is the low evaporation pressure, and various designs addressing this limitation were already tried in the last few years during transition from R507A to R452A and other alternatives. In this article 5 systems with R452A, two with R290 and two with R1270 are compared. The greatest effect was demonstrated by addition of roll-bond plates – it reduced the difference between the inside air and evaporation temperatures by about 3 K. However, this solution is not promising with hydrocarbons due to the higher refrigerant charge. All other solutions together give no more effect than roll-bond plates in terms of evaporation temperature at the end of pull-down. Based on experimental results, the prospects of eutectic refrigeration system with natural refrigerants are reviewed. R290 is not suitable for such systems, but R1270 could be used in systems where eutectic plates just need to be crystallized. However, in weight-optimized systems used in refrigerated vans, the evaporation pressure of R1270 would be lower than atmospheric, which is considered unacceptable due to safety requirements. If this provision remains, the eutectic refrigerators with a single-stage vapour compression refrigerating system become impossible, and more complicated cascade system has to be developed.

Simulation Study on Performance of Solar-Powered Desiccant Wheel and Ground Source Heat Pump Air Conditioning in Qingdao

In China, a large amount of the total energy consumption is made up of building energy, particularly in humid regions. The conventional vapor compression refrigeration systems cannot effectively control the indoor humid and thermal environment. Therefore, this article proposes a solar-powered desiccant wheel and ground-source heat pump (SDW-GSHP) air conditioning system. The energy consumption of the system is mainly from sustainable sources of solar and geothermal energy, showcasing excellent energy efficiency and environmental friendliness. The desiccant wheel (DW) processes latent heat loads, and the GSHP processes the sensible heat load. The regeneration air of the DW is heated by a solar collector. The operational performance of the system was simulated by using TRNSYS during the typical summer week (15 July to 22 July) in Qingdao. The simulation results indicated that indoor temperature was maintained within 25.8–26.2 °C and the relative humidity was maintained in the range of 57–61%. The COP of the SDW-GSHP air conditioning system was 42.1% higher than that of the DW air conditioning system with electric heating regeneration, and electricity saved 43.7%.

Agricultural Waste Valorization for Nanoparticles Synthesis and Enhancement of Vapour Compression Refrigeration System’s Performance

Waste management has been a major concern in the society and agricultural wastes can be utilized in the synthesis of nanoparticles and deployed in the vapour compression refrigeration system (VCRS) to enhance its performance. This study analysed the thermophysical properties, performance, energy consumption, pull-down time, and capacities of VCRS using bio-nanoparticles produced from orange and pineapple peels. Eco-friendly refrigerants R600a and R134a with pure polyolester (POE) as the lubricating oil for the compressor were used. The nanolubricants were dispersed in three volume fractions of 0.05%, 0.10% and 0.20% concentration in the lubricant using the two-step method. The degradation of nanolubricants were analysed by examining the thermophysical properties of the nanolubricants before and after use in the VCRS. At 0.2% volume concentration, optimum COP of 6.31 and 5.01 were obtained for pineapple and orange peels respectively for R600a. The nanolubricants of orange peels with the volume fraction of 0.2% had the best pull-down time with a temperature of-2oC. The lowest power consumption was observed for 0.1% volume concentration of pineapple nanolubricants while 0.2% volume concentration of orange nanolubricants was observed to have the least power consumption. Considering the R134a refrigerant, the volume concentration with the optimum COP was 0.1 vol% concentration for the orange bio-based nanolubricants with an increase in the COP of 36.3% when compared with pure R134a while 0.2 vol% had the best pull-down time with a temperature of-3oC. There was a 14.2% drop in the power consumption of 0.1 vol% concentration of pineapple nanolubricants when compared to the various concentrations of the bio-based nanolubricants. From this study, the optimum performance was observed at 0.20 vol% concentration for the orange and pineapple nanolubricants with a relatively less power consumption. R600a refrigerant can completely replace R134a in its use in refrigeration systems and achieve similar pull-down time and coefficient of performance when bio-nanolubricants are utilized in the systems.

Analysis of cascade vapor compression refrigeration system using nanorefrigerants: Energy, exergy, and environmental (3E)

Nanorefrigerants are considered the most efficient heat transfer fluids for improving heat transfer properties in the refrigeration and air conditioning equipment. For the first time in this study, energy, exergy, and environmental evaluation (3E) analyses were performed by the addition of different nanoparticles to a low GWP refrigerant pair such as R290/R1233ZDE in a cascade refrigeration system. CNT, CuO, and, TiO2 nanoparticles were added to the refrigerant. The effect of nanoparticles on the cascade refrigeration system was analyzed using a model based on density changes. A detailed thermodynamic analysis was performed of the cascade refrigeration system at different evaporator temperatures and mass ratios. The power consumption of the compressor decreases as the evaporator temperature increases for all types of nanoparticles, resulting in an increase in COP values. The analyses showed that CuO nanoparticles had the highest performance. It has been observed that the energy and exergy efficiency increase as compressor work decreases with increasing mass ratios in all nanorefrigerants. In addition, the results indicated that all nanorefrigerants emit lower monthly CO2 emissions compared to the pure refrigerants. The nanorefrigerants play a crucial role in reducing energy consumption and promoting environmental protection compared to traditional refrigerants.

A Review of Small-Scale Vapor Compression Refrigeration Technologies

The study and development of miniature refrigeration and climate conditioning systems based on vapor compression for small-scale applications have received wide interest in recent years due to their advantages compared with other available technologies, both active and passive. This paper identifies different applications and areas of opportunity, including electronic components and personal cooling, where small-scale vapor compression refrigeration systems are anticipated to play a key role in technological development. This paper presents the current state of the art, including applications, component designs, operating conditions, experiments, published results, etc. to describe the current status of small-scale vapor compression refrigeration and illustrate a perspective for the future of this technology.

Kinetic energy harvesting for enhancing sustainability of refrigerated transportation

The industry of temperature-controlled transportation has shown significant growth in recent years, and this growth is expected to continue in the future. As the sector expands, it's crucial to focus on reducing energy consumption and greenhouse gas emissions related to transport refrigeration systems to meet the planned decarbonization goals. In this study, the energy and environmental benefits of implementing an electric Kinetic Energy Recovery System (KERS) on a refrigerated light-duty commercial van, equipped with a vapor compression refrigeration (VCR) system, are assessed by means of dynamic simulation. The KERS considered involves a LiFePO4 battery as electricity storage system, a brushless motor-generator unit and a hybrid inverter able to both charge the battery and power the refrigeration system. For each component of the system, i.e. the engine, the alternator, the transmission system and the KERS, the real efficiencies have been considered. The dynamic behaviour of the KERS is simulated by using data obtained by performing a real urban single-delivery 40 km mission, during which the vehicle operating conditions, as well as the electricity demand of the refrigeration system, have been measured. The estimation of the potential benefits of the proposed solution has been performed by comparing the electricity produced by the KERS (and available for use) and the measured energy demand of the refrigeration system.The results have shown that the electricity available for use could cover more than 47% of the total electricity demand. This means that nearly half of the primary energy/fuel consumption can be saved by employing a KERS in refrigerated-light duty vehicles. In particular, emissions savings ranging between 9 and 13 gCO2,e and cost savings between 0.4 and 0.7 c€ per kilometer travelled can be achieved, resulting in an average payback period of 8 years. In addition, when considering the entire useful life of a refrigerated van equal to 10 years, CO2,e savings of 4515–6710 kgCO2,e are obtained.The low complexity of the proposed system and the availability of the components on the market, together with the results obtained by simulation, make using KERS in refrigerated transport a promising solution throughout the decarbonization of the refrigerated transport sector.

Influence of coupling air conditioner with hybrid PCMs on building interior conditions and consumed power: Experimental investigation

Air conditioning systems are vital for modern comfort but consume a substantial portion of global energy, contributing to environmental concerns and rising energy costs. PCMs can store and release energy during phase transitions, making them promise to reduce cooling loads. This study endeavors to empirically investigate the influence of integrating hybrid Phase Change Materials (PCMs), specifically PCMSP24E and PCMSP26E, with a real vapor compression refrigeration system. The primary focus is on assessing the consequential effects on the energy consumption of the refrigeration system and the interior environmental conditions within a building, including temperature and relative humidity. The energy usage of the split air conditioner wherein the outdoor unit is attached to PCMs tube heat exchanger for precooling the incoming air is investigated. Experiments reveal that PCM precooling effectively reduces the ambient air temperature entering the air conditioning condenser, leading to substantial energy savings. Increasing the PCM quantity enhances the system performance and refrigeration unit power saving. With 11 kg of PCMs, energy consumption by the air conditioning system decreases by 10.4 %, and indoor air temperature and relative humidity reduce by 0.5° and 5 %, respectively. Hence, PCM integration ensures a more consistent indoor temperature profile, enhancing occupant comfort and reducing temperature fluctuations.

LateSearching for the most energy-efficient composition of a mixture of dimethyl ether and carbon dioxide as an air conditioning system refrigerantr

BACKGROUND: Carbon dioxide can be an alternative refrigerant for vapor compression refrigeration systems, particularly air conditioning systems (ACSs). However, its use suffers from the increased pressure in the refrigeration circuit. To solve this, for its reduction, a mixture of CO2 with a substance that has significantly lower pressures under the same conditions can be developed, for example, dimethyl ether (DME), which has zero GWP and ODP, is inexpensive and readily available. The study of DME, in particular, was conducted by the Department E4 “Refrigeration and Cryogenic Engineering, Air Conditioning and Life Support Systems” of N.E. Bauman Moscow State Technical University. DME is moderately toxic and flammable.
 AIM: This study aims to investigate the possible use of a mixture of DME and carbon dioxide for energy-efficient application in ACSs using commercially available compressors for R410A.
 METHODS: Comparative calculation analysis of the characteristics of a simple one-stage vapor compression cycle was performed using R410A and a mixture of DME and CO2 using the calculation packages Mathcad 15, Aspen HYSYS v. 10, SOLKANE8, and REFPROP.
 RESULTS: 1. The cycle on pure DME is the most effective in terms of the coefficient of performance: ε = 5.63 at an ambient air temperature of 26°C, ε = 3.07 at 40°C. 2. It is necessary to consider the influence of temperature glides, the average value of which ranges from 10°C to 30°C depending on the concentration of components. 3. At DME/CO2 ratios of 40/60% and 60/40% (in mole fraction), the discharge pressure corresponds to the discharge pressure in the R410A cycle, with 39.62 bar at an ambient temperature of 26°C and 37 bar at 40°C, respectively.
 CONCLUSIONS: An environmentally friendly mixture of DME and CO2 with low GWP and zero ODP is developed. An increase in the percentage of DME in the mixture increases the coefficient of performance and reduces the pressure range, and at the same time, significant temperature glides arise, which affects the installation efficiency, namely, the transition to a cycle with a receiver tank, i.e., with a recuperative heat exchanger between the fluorinated refrigerant flow leaving the evaporator and the fluorinated refrigerant flow leaving the condenser. The developed mixture is less efficient than the R410A refrigerant in terms of the coefficient of performance and discharge pressure. However, it is possible to further consider a mixture of DME and CO2 with concentrations of 40% and 60%, respectively, as a replacement for the R410 refrigerant because there is a correspondence of discharge pressures for serial compressors (about 40 bar); however, it is necessary to keep in mind the flammability risk of the mixture.

Optimization of a three-stage cascade refrigeration system operating with natural refrigerants to produce low temperatures by applying a bio-inspired method

With the growing global energy consumption, on the first hand, and the need to produce low temperatures on the second hand, therefore the technological challenges consist in minimizing greenhouse gas emissions by reducing the energy consumption. In fact, in refrigeration, this consists of the use of environmentally friendly refrigerants (GWP < 150) with the optimization of cold production processes. In this context, several optimization methods have been tested, and the objective of this work to seek the most reliable method to optimize a three-stage cascade vapor compression refrigeration system. Regarding refrigerants, hydrocarbons can be a solution, the R50/R1150/R290 and R50/R1150/R1270 groups are selected and used here to produce temperatures ranging from −160 °C to −120 °C. After comparing seven (7) nature-inspired optimization methods, the JSOA bio-inspired optimization method is applied. Energetic, exergetic and environmental analyzes are also applied to determine the optimal operating point that allows both the minimization of energy consumption and TEWI (Total Equivalent Warming Impact). A pragmatic comparison between the two considered groups provides insights into the choice of high-temperature sub-cycle fluid, and it is found that R290 shows better results compared to R1270.

Dynamic simulation and control of dual-evaporator compression refrigeration systems

The need for refrigeration cooling at two different sub-ambient temperature levels is an important problem in some processes. A modern grocery store is an extremely important global example in which there is a need for a moderate temperature heat sink (5 °C) to keep food cool but also a need for a significantly colder heat sink (− 20 °C) for frozen food products. If the two temperatures are not too different, a single refrigerant can be used. The compression refrigeration configuration then consists of two compressors operating in parallel, a single condenser, a single refrigerant liquid surge drum and multiple evaporators. Liquid refrigerant at high pressure is split into a large number of parallel streams to feed individual evaporators in the cooling and freezing compartments. This paper studies how this multi-variable interacting dynamic system can be modeled and controlled using simple conventional controllers.

Analysis of the Vapor Compression Refrigeration Cycle Measures with and without Using a Heat Exchanger for Alternative Refrigerants

One of the most commonly refrigeration systems is the vapor compression refrigeration system. Since energy saving and environmental friendliness remain a challenge, researchers are working hard to find an effective solution to improve the performance of vapor compression refrigeration systems while committing to environmental standards. The main goal of this paper is to identify the best and closest alternative refrigerant to R22 among the alternative cooling fluids taken into consideration in terms of thermodynamic and mechanical properties, environmental protection, and safety of handling. This work presents an analysis and comparison of the various performance measures for a vapor compression refrigeration cycle operating without using and using a heat exchanger for environmentally friendly alternative refrigerants, namely R410A, R407A, R407C, R438, RS-44b, and R417A, and compares them with the refrigerant R22, which has direct environmental impacts on the ozone layer (ODP) and global warming (GWP). The computer simulation program Chemours Refrigerant Expert 1 was used to conduct the analyses. The performance parameters analyzed are coefficient of performance, compressor work, cooling capacity, temperature of condensation, intake and exhaust pressure, volumetric capacity, theoretical displacement, intake, exhaust, condensation and evaporation temperature without and with a heat exchanger, and super heating temperature with a heat exchanger. It was concluded from this study that the best alternative to R22 refrigerant among the alternative refrigerants taken into consideration in the study is the RS-44b refrigerant in terms of all performance measures and environmentally friendly. Keywords: Refrigerant; Vapor compression; Performance measures; Evaporation; Heat exchanger.