Refrigeration Technology Research Articles

A Review on Evaporator Modification in VCR System for Performance Enhancement

Abstract: This Review focuses on the design and fabrication of an evaporator with multiple isolated chambers for a refrigerator. The aim is to enhance the efficiency and performance of the refrigeration system by employing an innovative evaporator design. The literature review includes studies on various refrigerants, refrigeration systems, and the integration of advanced technologies like phase change materials (PCM), thermoelectric generators (TEG), and thermal energy storage (TES). These studies highlight the importance of optimizing refrigerant selection, improving heat transfer mechanisms, and addressing environmental concerns related to global warming potential (GWP) and ozone depletion potential (ODP). The project seeks to develop an evaporator with multiple isolated chambers, which can potentially offer better temperature control, increased heat transfer efficiency, and reduced energy consumption. By combining insights from previous research with practical fabrication techniques, this review aims to contribute to the advancement of refrigeration technology, ensuring both energy efficiency and environmental sustainability

Stable magnetocaloric effect over an ultrawide temperature range of 146–320 K via hydrostatic pressure in kagome magnets

Solid-state refrigeration leveraging the magnetocaloric effect (MCE) presents a sustainable and energy-efficient alternative to traditional gas compression refrigeration technologies. However, the practical utility of most magnetocaloric materials is restricted by their narrow operational temperature window. In this work, a stable magnetocaloric effect across an ultrawide temperature range of 146–320 K was achieved in Hf0.85Ta0.15Fe2 magnet via the hydrostatic pressure manipulation. Furthermore, the underlying mechanism for the extended and stable MCEs under hydrostatic pressure has been revealed by magnetization measurements and first-principles calculations. The material systems characterized by strong spin–lattice coupling exhibit considerable potential for externally manipulated hybrid-field-tuned magnetic properties and magnetocaloric performance, providing a convenient and practical approach for advancing applications in magnetic refrigeration technologies.

Revolution of Refrigeration with Smart Technology and Commercial Connected Coolers (Exploring the Future of Refrigeration)

The refrigeration industry has changed with the incorporation of smart technology and the introduction of commercial connected coolers. These are a class of advanced systems that apply IoT for improved efficiency in operation, energy consumption, and quality of products in many commercial industries such as retail, food storage, healthcare, and logistics. The features in smart connected coolers involve sensors, real-time monitoring, and automated control systems with advantages of predictive maintenance, remote monitoring, energy optimization, and data-driven decision-making. To be able to deploy those features into reality, several challenges like very high initial cost, integration complexity, and security-related issues must be met. This article will discuss the key elements comprising IoT-enabled coolers, their applications across industries, the benefits they will come with, and challenges organizations must surmount if IoT-enabled coolers are ever to reach their full potential. It also touches on future trends in refrigeration technology, focusing on innovative, sustainable, and smart solutions as key factors in commercial refrigeration. Keywords: smart refrigeration, commercial connected coolers, IoT-enabled coolers, energy optimization, predictive maintenance, real-time monitoring, refrigeration technology, IoT applications, smart cooling systems, commercial refrigeration, future trends, refrigeration innovation, industrial applications, and sustainability in refrigeration.

Giant inverse elastocaloric effect of n-alkanes imbedded in a carbon-frame for room temperature thermal management.

Solid-state refrigeration technology, which utilizes phase transition materials responsive to an external field through which heat is exchanged with the environment, serves as a promising alternative to traditional vapor-compression refrigeration technologies. However, many existing solid-state refrigeration materials are limited by low latent heat, large external driving forces, high thermal hysteresis, or low thermal conductivity, limiting practical applications. In this work, through molecular dynamics simulations and thermodynamic analysis, we predict giant inverse elastocaloric effects in the composited alkane and carbon nanotube/graphene architectures. At near room temperature under a moderate compressive stress of ∼75 MPa, the estimated adiabatic temperature change (ΔT) and isothermal entropy change (ΔS) reach ∼23 K and 200 J kg-1 K-1, respectively, demonstrating an excellent elastocaloric performance and efficiency. The refrigeration efficiency (ΔT/Δσ) and thermal conductivity (κ) are significantly improved by one order of magnitude, reaching ∼500 K GPa-1 and ∼12 W m-1 K-1, respectively. Moreover, the application of compressive strain is able to bear the giant reversible elastocaloric effect, achieving cooling and heating with minimal hysteresis effects and no mechanical fatigue. The present work provides atomic-scale insights and important guidance for the design of n-alkanes as the prototypical amorphous polymers with eCE for room temperature solid-state refrigeration.

Monte Carlo simulation of ammonia adsorption in nanoporous carbon: Optimal pore sizes for adsorption refrigeration applications

Climate change and the continual rise in cooling demand means more efficient and environmentally friendly refrigeration technologies are required more than ever. One attractive route to reducing future demand is to improve adsorption refrigeration technologies based on natural refrigerants such as ammonia. The choice of ammonia adsorbent plays an important role in achieving improved refrigeration efficiency and suitable operating conditions. This paper reports a detailed study on the role of pore size on thermal efficiency, desorption temperature and cooling capacity of ammonia–carbon adsorption refrigeration systems. Systematic Monte Carlo simulations were conducted to study ammonia adsorption in carbon slit-pores with pores sizes ranging from 0.5 nm to 3.0 nm. Simulations were carried out at temperatures between 0°C and 50°C and pressures up to 15.0 bar. It is found that nanoporous carbon with very small pore sizes is not a good adsorbent for thermally efficient adsorption refrigeration systems. However, carbon mesopores can provide higher refrigeration capacities and coefficients of performance together with lower desorption temperatures, thus offering the possibility of relying on low-grade thermal waste heat to drive the refrigeration process.

Anisotropic nanocellulose-based aerogels for radiative cooling.

To this day, energy conservation, emission reduction, and environmental protection continue to be goals pursued by humanity. Passive radiation cooling, as a zero-consumption refrigeration technology, offers substantial opportunities for reducing global energy consumption and carbon dioxide emissions. It is of great significance to develop high-performance passive radiation cooling materials from sustainable materials. In this work, polyvinyl alcohol (PVA) and nanocellulose fibers (CNFs) were used as raw materials to build a hydrophobic aerogel with high strength, satisfied heat insulation and qualified radiative cooling effect by freeze-casting. The obtained aerogel with borax/CNFs = 2: 5 by directional freezing processed excellent mechanical property (compressive strength = 291 KPa) under low density of 38.1 mg·cm-3. Furthermore, the hybrid aerogel exhibited hydrophobicity, enhancing its durability and practicability. Significantly, the aerogel exhibited high solar reflectivity (96.8 %) at 0.2-2.5 μm, high emissivity (97.2 %) across the entire atmospheric window, and good thermal insulation performance (34.56 mW·m-1·K-1). Subsequently, the radiative cooling effect of composites were evaluated, and the hybrid aerogel under sunlight was approximately 9 °C cooler than EPS in hot summer. Our research will provide insights into developing radiative cooling materials, and also provides great possibilities of cellulose-based aerogels for applications in energy conservation.

Analysis of a simple vapor compression and ejector refrigeration systems working with eco-friendly refrigerants

Transitioning to alternative refrigerants with low Global Warming Potential (GWP) in both vapor compression and ejector refrigeration systems emerges as a viable strategy to address the environmental impact associated with refrigeration technologies. This shift necessitates a thorough examination of factors such as thermodynamic performance, safety considerations, and optimization of system design. The outcomes of this study contribute to the advancement of sustainable refrigeration systems, aligning with global initiatives to curb greenhouse gas emissions and preserve the environment. The study adopts a thermodynamic approach to numerically investigate several eco-friendly refrigerants with GWP below 150, including R1234yf, R1234ze, R1270, R152a, R290, and R600a, as potential alternatives for vapor compression and ejector refrigeration systems. Thermodynamic models, developed in MATLAB using refrigerant properties, reveal that R600a and R290 exhibit promising potential as replacements for R134a in vapor compression refrigeration systems. These alternatives demonstrate a noteworthy improvement in the thermodynamic coefficient of performance, with percentages of 2.47% and 2.12%, respectively, under similar working conditions. For ejector refrigeration systems, R152a, R717, and R1270 exhibit enhanced coefficients of performance, contributing to significant savings in generator heat load. The results highlight the ability of these refrigerants to improve both the efficiency and sustainability of refrigeration systems in diverse applications.

Cooling of animal products in an air-gas environment of carbon dioxide

In our country, as well as throughout the world, special attention is paid to finding more modern, energy-efficient and environmentally friendly methods of cooling food products, including animal ones. The basis of most technological processes of refrigeration treatment is working fluids, which can be natural or synthetic substances. Due to the negative impact of synthetic raw materials on the environment, preference is given to substances of natural origin. The greatest interest in the last twenty years in the world community of refrigeration equipment and technology is shown to carbon dioxide. This refrigerant is actively used in traditional vapor-compression refrigeration machines. In Russia carbon dioxide as a working substance in closed cycles of refrigeration machines is found at industrial facilities whose operation is based on cascade cycles. In this case, carbon dioxide acts as a working substance of the lower cascade, since it belongs to high-pressure refrigerating agents. Until 2022, carbon dioxide-based refrigerants were also actively developed at transcritical temperature levels, where the condensation temperature of carbon dioxide is close to ambient temperatures. In this study, carbon dioxide will be considered as a refrigerant when it interacts with the product in an air-gas environment during sublimation, in which carbon dioxide changes its aggregate state from snow-like to gaseous.

Research on multi-space portable box based on thermoelectric refrigeration technology

Research on multi-space portable box based on thermoelectric refrigeration technology

An efficient low-grade thermal energy dual-driven elastocaloric cooling system: Thermodynamic cycle analysis, economic and sustainability assessment

Elastocaloric cooling is regarded as the most promising emerging refrigeration technology, with heat driven elastocaloric cycles at the forefront of research. However, existing systems often have actuators with a mass of 4–20 times that of the refrigerant, resulting in bulky structures and low thermodynamic efficiency. Enhancing system compactness and efficiency has thus become a critical research challenge. This study proposes an innovative low-grade thermal energy dual-driven elastocaloric cooling system, achieving a 1:1 mass ratio (mActuator/mRefrigerant) between the actuator and refrigerant, significantly improving system compactness and coefficient of performance while effectively reducing costs. A three-dimensional numerical and geometric model was developed to analyze the thermodynamic cycle, examining the effects of material, operational, and geometric parameters on cooling performance, and a “category-wise optimization” strategy was employed to determine optimal parameter combinations. The cost and environmental impacts of the new system were evaluated and compared with vapor-compression air conditioning. Results show that the difference in transformation temperatures between austenite and martensite phases significantly impacts cooling performance. Optimal flow rates and cycling frequencies are essential to avoid performance loss. Considering the coefficient of performance and heat transfer, a 1:1 mass ratio is optimal for geometric parameters. The system achieves a maximum coefficient of performance of 0.158, exceeding the existing two schemes by more than 2 times and 7 times, with a maximum temperature rise of 13.1 K. The proposed system is economically feasible and environmentally friendly, providing valuable theoretical foundations and technical solutions for developing sustainable alternative refrigeration technologies.

Modulation of BixSb2-xTe3 Alloy Application Temperature via Optimizing Material Composition.

Bi2Te3-based alloys are representatively commercialized thermoelectric materials for refrigeration and power generation. Refrigeration mainly utilizes thermoelectric properties near room temperature, while the power generation temperature is relatively high. However, it is difficult for bismuth telluride to maintain good thermoelectric properties throughout the entire temperature range of 300-500 K. Herein, a series of BixSb2-xTe3 alloys with different Bi contents were prepared by a simple preparation method and systematically investigated, and their best application temperature range was found. The Bi content can modulate carrier concentration and band gap, and the maximum dimensionless figure of merit (ZT) value of BixSb2-xTe3 can be achieved in the corresponding application temperature range. The maximum ZT of Bi0.3Sb1.7Te3 with a Bi content equal to 0.3 reaches 1.14 at 400 K, and the average ZT is 1.06 in the range of 300-500 K, which is suitable for both power generation and refrigeration. Therefore, power generation technologies with higher application temperatures should be selected from BixSb2-xTe3 materials with Bi content less than 0.3, and refrigeration technologies with lower application temperatures should be selected with Bi content greater than 0.3. This work provides experimental guidance for finding the composition of Bi2Te3-based alloys in scientific research and practical applications.

Performance investigations of the easily manufactured composite all-day radiative cooling materials based on PDMS

The passive radiative cooling technology can be employed to obtain the cooling capacity without any energy consumption, which has been garnering significant attention nowadays. This work proposes and experimentally studies the all-day radiative cooling material based on layered composite material made from Polydimethylsiloxane (PDMS). This work adds SiO2 nano-particles, which act as visible light scatters, and the proposed film can realize an excellent all-day cooling capacity when the thicknesses of the PDMS and Al films are respectively chosen as 200 μm and 4 μm, and the concentration of the SiO2 particles in the film is 40 %. The theoretical explorations indicated that the presented composite film can exhibit the high reflectivity (90.36 %) and emissivity (90.19 %) in the visible spectrum and atmospheric transparency window (ATW) spectrum. Under direct sunlight of a highest solar irradiance of 688.89 W/m2, there is an average temperature difference between cooling film and white paper of 6.3 °C. Furthermore, in clear weather conditions at night with an average humidity level of 58.15 %, it can generate a temperature difference of 4.8 °C. This work proposes an easily manufactured and eco-friendly all-day radiative cooling material, which has the potential applications in future refrigeration technology.

Exergy-economic based multi-objective optimization and carbon footprint analysis of solar thermal refrigeration systems

The increasing carbon footprint associated with conventional cooling methods underscores the urgent need for sustainable alternatives. This study investigates the economic and environmental advantages of various solar-thermal cooling systems, with a focus on optimizing their performance across different climate conditions. Employing a multi-objective approach, the research emphasizes exergy-economic indices to optimize selected cycles. The analysis covers multiple refrigeration technologies, including liquid absorption, solid adsorption, and solid desiccant cycles. Results indicate that the liquid absorption cycle performs optimally in hot, arid climates, reducing the payback period to approximately 8 years when optimized. In hot and humid regions, the solid desiccant cycle proves most effective due to its superior humidity control, yielding a payback period of 5.3 years. For cold and mountainous areas, the solid adsorption cycle is preferred, with a payback period of 13.5 years, while moderate and humid climates benefit from the solid desiccant cycle for both cooling and humidity regulation. The exergy-economic factors for the solar refrigeration systems across semi-arid, hot and arid, hot and humid, cold and mountainous, and moderate and humid climates are 0.758, 0.602, 0.698, 0.74, and 0.575, respectively.

Achieving off-grid refrigeration in remote areas: A solar-powered vapor compression refrigerator prototype with PCM integration

The availability of vaccines, medicines, and perishable goods in remote or off-grid areas remains a formidable challenge. Integrating solar photovoltaic (PV) systems with refrigeration technology has emerged as a promising solution to address this critical need. This paper presents an autonomous solar-powered refrigerator prototype for off-grid refrigeration in remote areas utilising renewable energy. The system comprises a 160 W photovoltaic module, a 12/24 V DC compressor refrigerator, a lead-acid battery, and a Maximum Power Point Tracking (MPPT) controller. Its main feature is complete autonomy from the electricity grid, thanks to its standalone configuration. An experimental campaign evaluated the system's behaviour in the laboratory for 24 h at different set-point temperatures. A water-based Phase Change Material (PCM) was implemented to improve its autonomy in severe outdoor conditions. A further experimental campaign emulated the functioning of the prototype while managing the temperature of a sample solution whose melting temperature was equal to – 21 °C to ensure its liquid state during the tests. The target range for preserving the sample was defined at ± 1 °C. Several real conditions have been considered, such as higher cooling loads realised through 21 litres of additional thermal mass in the refrigerator and pick and place conditions for simulating the opening and closing of the door. The results demonstrate that the solar refrigerator prototype achieves complete autonomy from the electricity grid, paving the way for solutions for preserving perishable goods such as medicines and food in unelectrified areas.

Calculation of exergy losses, exergy efficiency and cooling coefficient of refrigerant R22

This study presents a detailed analysis of the exergy losses, exergy efficiency, and cooling coefficient of performance (COP) for the refrigerant R22 in refrigeration systems. Exergy analysis, which considers both the quantity and quality of energy, is used to identify and quantify the irreversibilities within the system. The objective of this analysis is to provide insights into the areas of inefficiency and potential improvements for enhanced energy performance. Results indicate that the exergy losses in R22 systems are primarily associated with the compressor and expansion valve, highlighting these components as key targets for efficiency improvements. The exergy efficiency was found to vary significantly with operating conditions, suggesting that system performance could be optimized through appropriate design and control strategies. Additionally, the cooling COP of R22 was evaluated, demonstrating its effectiveness in converting input energy into cooling capacity under various conditions. This analysis contributes to the broader understanding of R22's thermodynamic performance and offers a foundation for developing more sustainable and efficient refrigeration technologies.

Time dependent model to analyze the magnetic refrigeration performance of gadolinium near the room temperature

Abstract A practical time-dependent model has been constructed to forecast the effectiveness and productivity of a magnetic regenerative refrigerator, as well as to assess its cycle efficiency. The model incorporates many irreversible factors, including the cycle frequency, heat transfer efficiency, and heat leak. Furthermore, it is utilized to scrutinize a magnetic refrigerator that employs spherical Gd particles as the magnetic substance and water as the heat transfer medium. The different cycle steps of the magnetic refrigerator are examined, while the cooling capacity and temperature differential between the two heat exchangers are appraised. The results also show that the magnetic refrigerator can obtain a temperature span of 5 K under 0.8 T magnetic field after 30 cycles in a particular situation. The findings provide valuable information for the future planning and advancement of magnetic refrigeration technology at room temperature.

A point of view of the elastocaloric effect associated with 7M and 5M modulated martensite in Ni–Mn–Ga alloys

Solid-state refrigeration has emerged as the most promising alternative to conventional refrigeration technology. However, for this technology to be applicable, the caloric effects produced in the alloys must be highly reversible. In this context, we compare the elastocaloric effect of two Ni–Mn–Ga alloys with different types of modulated martensite. The elastocaloric effect, quantified as the isothermal entropy change (ΔSela), was investigated in Ni50Mn28Ga22 and Ni50Mn30Ga20 alloys with 5M and 7M modulated martensite, respectively. Maximum ΔSela values obtained were 1.91 J kg−1 K−1 during cooling and 1.83 J kg−1 K−1 during heating in martensite 5M and 0.19 J kg−1 K−1 during cooling and 0.26 J kg−1 K−1 during heating in martensite 7M, for a constant applied stress of 10 MPa. However, although the 7M modulated martensite exhibited a lower ΔSela, its reversibility was higher. Therefore, our results could be useful for selecting a good material to be used in solid-state refrigeration.

Anomalous electrocaloric behaviors in (anti)ferroelectrics: a mini-review.

Solid-state cooling, represented by the electrocaloric effect (ECE) in (anti)ferroelectric materials, has emerged as an alternative green refrigeration technology by virtue of its high efficiency and miniaturization and is expected to substitute conventional vapor-compression. Significant progress has been made in developing high-performance EC materials since its revival. However, anomalous EC behaviors are frequently observed, including asymmetric and negative EC profiles, and the physical mechanism behind this is still under debate. Its rationalization is of great importance since full utilization of anomalous EC behaviors could enhance EC strength and/or cooling capacity. This mini-review gives a brief overview of research advances in EC anomalies in (anti)ferroelectrics with the hope of provoking thought on the design of reconstructed refrigeration cycles and superior EC materials for application in solid-state cooling devices.

The crystal structures, magnetic interactions and cryogenic magnetocaloric effects for NaGdXO4 (X=Si, Ti) compounds

The development of ultra-low temperature magnetic refrigeration technologies demands magnetic refrigeration materials with excellent properties. Hence, improving performances of magnetic refrigerants has always been a significant scientific issue in magnetic refrigeration field. In this article, the relationship of crystal structures, magnetic interactions and magnetocaloric effect (MCE) for NaGdSiO4 and NaGdTiO4 has been investigated. NaGdSiO4 and NaGdTiO4 both crystallizes orthogonal structure, but the significant difference of unit cell parameters and symmetries results in different arrangement of Gd atoms. The distorted crystal structure and weaker magnetic between Gd3+ ions make NaGdSiO4 exhibit larger MCE with the maximum magnetic entropy change (-∆SM) of 49.0 J·kg−1·K−1 at 2.8 K. Comparably speaking, NaGdTiO4, which is a quasi-triangular antiferromagnet, possesses a stronger magnetic interaction between Gd3+ ions with the maximum -∆SM of 31.9 J·kg−1·K−1 at 2.6 K. These results confirm the importance of magnetic interactions for magnetic refrigeration materials, and, more broadly, they highlight the significance of crystal structures in that field.

Investigation of second-order magnetic transition and thermal hysteresis in cobalt-substituted Ce[formula omitted]Fe17 magnetocaloric compound

Understanding the fundamental properties of second-order magnetic transitions and thermal hysteresis in iron-rich magneto-caloric materials is crucial for developing efficient and eco-friendly refrigeration technologies. This paper focuses on the investigation of the intermetallic compound Ce2Fe16.4Co0.6. The study aims to transform the heli-magnetism of Ce2Fe17 into the desired ferromagnetic behavior and understand the nature of the ferromagnetic paramagnetic transition. To achieve this, a combination of techniques such as X-ray diffraction, direct magnetization measurement, and experimental results were compared with different theoretical models. X-ray diffraction shows that both compounds are of high purity and single-phase, X-ray diffraction coupled with Rietveld refinement indicates that Ce2Fe16.4Co0.6 and Ce2Fe17 have a rhombohedral crystal structure and crystallize in the space group R3̄m. Adding a small content of cobalt leads to a ferromagnetic order with a Curie temperature equal to ∼ 270K. Since there is an ambiguity regarding the order of the phase transition, it has been studied with different methods such as thermal hysteresis, Baneerje’s criterion, Landau’s phenomenological model, Bean–Rodbell model. To provide more details about the nature of the transition and its universality class, we have made a detailed study of the critical behavior. We find that the critical exponent β is close to that predicted by the 3D-Heisenberg model while the exponent γ is close to that predicted by the 3D-Ising model.