Vapor Compression Refrigeration Research Articles

Enhancing Vapor Compression Refrigeration Systems Efficiency via Two-Phase Length and Superheat Evaporator MIMO Control

The present investigation focuses on enhancing the efficiency of a vapor compression refrigeration system (VCRS) by proposing a Multiple Input Multiple Output (MIMO) control strategy based on the evaporator’s two-phase length and superheat temperature. A moving boundary dynamic model for the VCRS is implemented using the Thermosys Matlab Toolbox. The study analyzes the influence of actuation parameters, specifically compressor speed and expansion valve opening, on control parameters, namely two-phase length and superheat temperature. A comprehensive analysis based on the first and second laws of thermodynamics is conducted across a wide range of operating conditions. Simulation results demonstrate that two-phase length can be effectively utilized as a control parameter by selecting operating points that maximize the system efficiency. Additionally, the study reveals that extending the evaporator’s two-phase length to 80–90% of its limit increases system efficiency, enabling a reduction in compressor speed while maintaining the cooling capacity.

Parametric influence and optimization of the dehumidification performance of a variable-frequency dehumidifier

This paper optimizes a variable-frequency dehumidification system (VFDS) based on the principle of vapor compression refrigeration (VCR), wherein the compressor frequency and fan speed can be changed. The effect of the compressor frequency and fan speed on the operating parameters of the VFDS, including the evaporating temperature (T e), condensing temperature (T c), superheating (ΔT sh), and subcooling (ΔT sc), is studied experimentally under three operating conditions. The effect of variable-frequency on the dehumidification performance is analyzed at the mechanistic level through two dehumidification performance indicators, namely, the dehumidification capacity (DC) and dehumidification energy efficiency (DEE). ΔT sh is primarily controlled by the capillary throttling effect, which always starts to cross the “0” point when the fan speed is 600 rpm under different conditions. An increase in the compressor frequency leads to the opposite trend for DC and DEE, but their corresponding optimal fan speeds are relatively close. At 27 °C/60%, the optimal fan speed intervals with DC and DEE as single optimization objectives are both [600 rpm, 700 rpm]. However, at 30 °C/80%, the overall difference between the optimal fan speed intervals with DC and DEE as optimization objectives is 50–100 rpm. Importantly, the risk of frost at 18.3 °C/60% can lead to a significant extension of the optimal fan speed interval, which is [500 rpm, 900 rpm], making it more difficult to control. The concept of the dehumidification operating temperature difference (ΔT) is proposed to comprehensively evaluate the dehumidification capacity and as a control index for variable frequencies. The relationships among the optimal ΔT and the ambient dew point temperature (Td ) and compressor frequency are established through response surface methodology (RSM) with a maximum deviation of 5.97%. This work can provide an optimized variable-frequency solution for the VFDS and some guidance for the control logic development of the VFDS.

Large magnetocaloric refrigeration performance near room temperature in monolayer transition metal dihalides

Magnetocaloric effect (MCE) exhibits highly efficient and ecological cooling abilities for solid-state refrigeration in contrast to traditional vapor-compression refrigeration. Successive emerging two-dimensional (2D) magnetic materials provide a fertile platform for exploring low-dimensional MCE systems. Here, we focus on a series of 2D transition metal dihalides MX2 (M = Fe, Ru, Os; X = Cl, Br) to explore the maximum isothermal magnetic entropy change (−ΔSmagmax) and adiabatic temperature change (ΔTadmax) under external magnetic field. It is found that FeCl2, FeBr2, and RuCl2 have intrinsically sizable −ΔSmagmax, ΔTadmax, and high thermal conductivity near room temperature, demonstrating superior comprehensive refrigeration performance in comparison with other 2D magnets. It is revealed that strong nearest-neighbor ferromagnetic exchange interaction plays a decisive role in −ΔSmagmax, and the high lattice thermal conductivities of FeCl2 and RuCl2 are attributed to the longer phonon lifetime and larger group velocity of low-frequency acoustic branch. Moreover, moderate strain and carriers doping are able to effectively regulate Curie temperature and magnetocrystalline anisotropy energy and correspondingly enhance −ΔSmagmax. The present work provides important insights for the exploration of 2D magnets for magnetocaloric refrigeration near room temperature.

A high performance solar-assisted ejector expansion refrigeration cycle for residential air conditioning

Introducing a solar collector between the compressor and condenser of an ejector expansion refrigeration cycle (EErc) can improve the performance of the system by further superheating the refrigerant. Hence, this paper proposes a new configuration of a vapor compression refrigeration system, solar compression-ejector expansion refrigeration cycle (SCEErc) with energy saving in the compressor via an ejector and an evacuated tube solar collector. The performance improvement of the proposed system under a wide range of operating conditions such as condenser and evaporator temperatures, superheating and subcooling degrees, nozzle and diffuser efficiencies, and solar radiation intensities has been evaluated and compared with EErc under the same operational conditions and for four different refrigerants. The results indicate that the coefficient of performance (COP) of the SCEErc increased by 26.53 % compared to the EErc for the solar radiation energy of 0.2 kW. Moreover, exergy analysis results indicate a 59 % increase in the exergy destruction of the condenser in the SCEErc compared to the EErc. This is due to the increase in heat rejected from the condenser to the environment, which can be beneficial if the condenser cooling air outlet is utilized for applications like heat recovery technologies. The R152a, boasting a COP of 3.963, presents itself as a more favorable alternative to R134a.

Design Models of Equipment Vapor Compression Refrigeration Cycle To Support Practicum Heat Engine And Fluid Engineering

Design Models of Equipment Vapor Compression Refrigeration Cycle To Support Practicum Heat Engine And Fluid Engineering

Colossal Barocaloric Effect near Ambient Temperature in 1-Dodecanol under a Low Pressure.

Solid-state refrigeration based on the barocaloric effect is an effective alternative to traditional vapor compression refrigeration. Here 1-dodecanol has been studied due to its large latent heat at a solid-liquid phase transition point around room temperature. The transition temperature will vary with the applied hydrostatic pressure, exhibiting with a sensitivity of 0.14 K MPa-1, which indicates its potential for refrigeration. A pressure of 40 MPa can result in a large isothermal entropy change of 520 J kg-1 K-1 (equivalent to that obtained in vapor compression refrigeration) at 297 K. A large adiabatic temperature change of >20 K in 1-dodecanol was acquired by direct measurement. A wide temperature window of ∼50 K (288-337 K) can be obtained in 1-dodecanol, which demonstrates broad application prospects. These discoveries offer promising prospects for barocaloric cooling and high-efficiency refrigeration technologies relying on solid-liquid phase transitions.

Proposal of a novel multi-generation system based on dual-loop absorption power and compression refrigeration cycle

One of the promising approaches to compensate for imminent depletion of fossil energy resources and their adverse global impacts is enhancing the efficiency of systems utilizing low-temperature heat sources. The initial target of the research is to present a promising system for simultaneous production of power, refrigeration, heat, and hydrogen utilizing a combination of the absorption power cycle, the vapor compression refrigeration cycle, and a proton exchange membrane electrolyzer. On this subject, a comprehensive modeling of the energy and exergy of the proposed set-up is presented, and its thermodynamic performance is scrutinized. Furthermore, a comprehensive study of various parameters is performed to evaluate their impacts on system performance. The research aims to enhance and optimize the use of energy and various resources, contributing to the development of more sustainable efficient energy systems. Thermodynamic analysis of the multiple generation system shows that under baseline conditions and initial design, the system has the capability to produce net electrical power of approximately 17.12 kilowatts, cooling power of about 201.5 kilowatts, heating power of around 697.1 kilowatts, and produce pure hydrogen at a rate of 0.153 kilograms per hour. The system exhibits an energy efficiency ratio of 1.364 and an exergy efficiency of 36.58%. Moreover, optimization with single and multiple objectives with different weighting coefficients reveals that higher values of these parameters can be obtained. In other words, in the MOOM optimization mode, exergy efficiency increases to 7.16%, and the energy performance ratio rises to 85.73% compared to the BM mode. Additionally, through a parametric assessment to define the effect of input parameters on system performance, it demonstrates that increasing the temperature of the heat source may simultaneously increase the exergy efficiency and energy performance ratio of the system. The Grassmann diagram also indicates that the total exergy of the input fuel is about 196.9 kilowatts. From this amount, approximately 121.5 kilowatts are destroyed through the components of the system. Furthermore, about 3.39 kilowatts are lost through the absorber coolant and waste from the hydrogen production unit. About 72.4 kilowatts are attributed to products.

Giant electrocaloric effect and breakdown field strength in ferroelectric terpolymer nanocomposites by morphologically diverse nanostructures

Electrocaloric cooling is a method for flexible electronics and compact chips with a promising ability to subvert traditional vapor compression refrigeration technology. Nevertheless, most reported EC materials exhibit relatively low adiabatic temperature (ΔT) and low breakdown field strength (Eb) at room temperature, limiting their further applications. Here, we develop a ferroelectric nanocomposite, composed of relaxor terpolymer poly(vinylidene fluoride-trifluoroethylen-chlorofluoroethylene) (PVTC), ceramic nanofillers [0.68(BaZr0.2Ti0.8O3)-0.32(Ba0.7Ca0.3TiO3)] (BCZT), boron nitride nanosheets (BNNSs), and BiFeO3 nanofibers (BFO NFs) with different morphologies and vary components ratios. The most optimal 12BBBP nanocomposite demonstrates gigantic ECE values including an isothermal entropy change (ΔS) of 94.5 J·kg−1·K−1 and a ΔT of 13.5 K under 220 MV/m electric field at 303 K, ΔS and ΔT are 3.5 times and 2.2 times larger than PVTC under 100 MV/m. It also exhibits an excellent Eb with a value of 290 MV/m. The phase-field simulation is used to simulate Eb behavior of nanocomposites with fillers of different nano-morphologies under an electrostatic field. Simultaneously, the interfacial coupling and ferroelectric domain structures are also simulated based on the time-dependent Landau-Ginzburg-Devonshire (TLGD) theory through finite element analysis (FEA) to present a better explanation for ECE performance. The experimental and simulation results simultaneously denote the ferroelectric nanocomposite possesses outstanding ECE and high Eb performance, laying foundation for the ferroelectrics in fields of flexible electronics and compact chip cooling. Coupled with the facile processability of terpolymer and lead-free nature of electroactive ceramics, this work paves a new way to develop a scalable, environmentally friendly and high-performance EC materials for next generation of refrigeration.

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.

Techno-economic analysis of blue ammonia synthesis using cryogenic CO2 capture Process-A Danish case investigation

Ammonia is a vital chemical with numerous applications. Currently, the primary methods for generating the necessary reactants for ammonia production involve steam methane reforming (SMR) and cryogenic air separation unit (CASU), while the Haber-Bosch process converts these reactants into ammonia. However, the SMR process releases substantial amounts of CO2, making it imperative to employ an efficient and cost-effective CO2 capture technology to mitigate emissions. This investigation focuses on evaluating the cryogenic CO2 capture (CCC) process for blue ammonia production and provides a thorough economic analysis, estimating both the initial investment costs and operational expenses involved in producing blue ammonia. The results indicated that the CCC process can capture 90% of the CO2 content in the flue gas emitted by the SMR, incurring an energy penalty of 0.724 MJe/kgCO2 while capturing CO2 in the liquid phase with purities exceeding 99.9%. In this case, the estimated CO2 capture costs would be 18.05, 45.1, and 16.65 USD/ton in 2021, 2022, and 2023, respectively. This represents a 40% reduction compared to the CO2 capture costs associated with conventional amine-based technology. The results of this study indicate that the annual electricity costs for ammonia production increase by 38.5% and 64.2% when employing the CCC and amine-based processes, respectively. This investigation employed an isothermal reactor for ammonia synthesis, using the heat from the exothermic reaction in a water ammonia absorption refrigeration cycle (ARC) to condense and purify ammonia. The results show that the ARC system can effectively condense ammonia at −6 °C, producing a liquid ammonia stream with 99.3% purity. This leads to a 95% reduction in power consumption compared to a vapor compression refrigeration cycle (VCRC). Consequently, this method has the potential to decrease the annual operational costs for ammonia production by 2.92%, 2.69%, and 3.13% in 2021, 2022, and 2023, respectively. This study indicated that the hydrogen production unit incurs the highest initial investment costs, as well as operating costs, in the blue ammonia production process, followed by CASU and the Haber-Bosch process.

Thermodynamic performance analysis and environmental impact assessment of cascade refrigeration cycles using eco-friendly nano-refrigerants

There is a lack of research in the literature on the application of nanoparticles to different cascade cycle configurations with environmental refrigerants in ultra-low temperature refrigeration applications. This study is the first on the use of nano-refrigerants in cascade refrigeration cycles. In this study, the effect of 2 wt.% of CuO to RE170 and R170-pure refrigerant utilization in cascade vapor compression refrigeration cycle (CVCRC), cascade ejector refrigeration cycle (CERC) and cascade ejector intercooler refrigeration cycle (CEIRC) are investigated to achieve higher performance values in ultra-low temperature applications. For CVCRC, CERC and CEIRC, the increases in terms of coefficient of performance (COP) with the use of nano-refrigerant were found to be 12.77 %, 8.20 %, and 6.37 %, respectively, and 18.55 %, 14.05 %, and 6.07 %, for exergy efficiency. Upon scrutinizing the results with nano-refrigerant in relation to the COP, the analysis revealed that the CEIRC cycle exhibited an improvement ranging from 13.43 % to 20.49 % in comparison to CERC. Additionally, with nano-refrigerant, the CEIRC cycle demonstrated an increase ranging from 42.39 % to 75.41 % when compared to CVCRC in COP. It was observed that the utilization of CEIRC led to a 13.03 % decrease in kg CO2 emissions in compared to CERC and a reduction of 32.53 % compared to CVCRC with using nano-refrigerant.

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.

Compression-assisted absorption refrigeration cycle employing organic working pairs for ultra-low grade heat recovery

Solar absorption refrigeration technology is considered an ideal alternative to energy-intensive refrigerated warehouses due to its decarbonization and environmental friendliness. However, it faces challenges in competing with vapor compression refrigeration, such as high driving heat source temperature (>100°C) and a long payback period. In this paper, we address these challenges by focusing on cycle structure and working pair, and propose a compression-assisted absorption refrigeration cycle (CARC) using R32/dimethylacetamide (DMAC) as working pair. The aim is to significantly reduce driving heat source temperature by adjusting absorption pressure utilizing an auxiliary compressor, enabling the cycle to be connected to low-cost and efficient non-concentrating solar collectors, thereby effectively shortening its payback period. This cycle includes two operating modes: CARC mode powered by solar energy during the daytime and vapor compression refrigeration cycle mode driven by off-peak electricity at night, ensuring 24-hour cooling capacity for refrigerated warehouses. The results indicate that this cycle can flexibly utilize 60∼80°C solar hot water easily obtained as driving heat source and its evaporation temperature decreases to -20°C. To assess its performance benefits, a compression-assisted absorption refrigeration system is developed and implemented. By utilizing the limited roof area of a refrigerated warehouse, it can achieve an 18.2% reduction in electricity consumption and a 24.2% reduction in carbon emissions compared to the vapor compression one annually. Additionally, during peak electricity demand periods in summer, the system exhibits significant energy-saving effects, and its payback period is about 4.2 years. Ultimately, this cycle provides a viable solution for energy-saving and emission reduction in refrigerated warehouses.

A review of internal cooling strategies in liquid desiccant dehumidification and cooling systems

Air conditioning systems have become an integral part of society, and their utilization is increasing day by day. Most air conditioning systems use the vapor compression refrigeration (VCR) principle, which is a 190-year-old technology and has undergone significant changes to improve its performance and efficiency. However, the major drawback of VCR is its high energy consumption and use of highly polluting refrigerants. In this 21st century, energy conservation and environmental protection are the need of the hour. To mitigate the challenges, the search for alternative cooling systems that are eco-friendly and have less energy consumption is gaining wide attention. Liquid desiccant systems are gaining popularity due to less energy consumption and being eco-friendly. Therefore, this study attempts to review the recent developments in liquid desiccant technology by focusing on internal cooling strategies. As the internal cooling improves the overall performance of the liquid desiccant by controlling the liquid temperatures. Therefore, this review highlights the various methods, configurations and mathematical simulations in internal cooling, which are less explored in the available literature.

Numerical modelling of a hybrid vapor compression refrigeration assisted closed loop liquid cooling system for high-performance computing systems

This study presents a numerical model of a miniature vapor compression refrigeration (VCR) system that is used to cool liquid coolant in a secondary pumped loop that is deployed to cool a high-powered CPU. The model employs a physical approach and iterative algorithms to solve coupled non-linear equations for both the refrigeration cycle and pumped single phase cooling loop. Experimental tests were conducted to verify the model using an in-house test facility. This paper outlines the modelling and solution approaches taken, discusses the efficacy of the model in terms of agreement with experimental measurements, and highlights the utility of the model as a design tool for cooling high powered electronics.

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.

Magnetocaloric refrigerator with magnetic pump and liquid metals

One-seventh of the worldwide electricity is used for refrigeration related activities. When compared to the predominantly used vapor compression refrigeration system, magnetocaloric refrigeration provides an energy-efficient and eco-friendly alternative. It utilizes a magnetocaloric material which undergoes temperature changes when exposed to magnetic field changes. Nearly 60% of the total system cost is due to the permanent magnets used. For a given cooling power, the amount of permanent magnet needed is determined by the residence time required by the heat transfer fluid in each cycle. The start-of-the-art systems utilizes water-alcohol mixture as the heat transfer fluid, and a mechanical pump for its circulation. By utilizing non-toxic and non-hazardous gallium-indium-tin based liquid metals as heat transfer fluid, which has three order of magnitude higher thermal diffusivity, the residence time and the permanent magnetic material is reduced nearly by a factor of 10. Even accounting for the cost of the liquid metal, it results in considerable savings in the system cost. We present experimental results on the entropy change of using liquid metal with (Mn,Fe)2(P,Si)-based magnetocaloric material, and numerical results on the system level analysis. Further, to improve the reliability of the system, we propose to use magnetic pumping for heat transfer fluid circulation, which does not have any moving parts. The state-of-the art magnetic pump works at frequencies in the range of 100 to 1000 Hz. However, they cause detrimental heating effects due to eddy current losses. To overcome this, we have designed a pump that operates at 1 Hz and still achieves comparable flow rates. We present numerical results on the pump design by studying the dynamics of ferrofluid rise in a vertical pipe with multiple electromagnetic coils.

State of the art of micro vapour-compression systems

Thermal management is becoming more challenging due to the increasing compactness and computational power of appliances. Affordable and efficient solutions include active liquid cooling methods, thermoelectric cooling, and the use of heat pipes. From these, vapour-compression technologies achieve the highest power density. However, the downscaling of vapour-compression for cooling of personal computers or workstations is rather problematic from several different reasons. The first problem concerns the low second law efficiency of miniature vapour-compression systems. The second problem concerns the available space occupation of such a cooling system. Moreover, miniature and high-power density condensers and evaporators have not yet been adequately researched and developed to date. In this review, we present several vapour-compression refrigeration systems that are based in some way on the miniaturisation of systems or individual components – evaporators, condensers, and compressors. These are presented and compared in terms of cooling power, COP, and the second law efficiency. At the end of the manuscript, guidelines for future improvements and the implementation of miniature vapour-compression systems are presented.

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.