Design Of Refrigeration System Research Articles

Thermodynamic modeling and performance optimization of transcritical CO2 dual-evaporator refrigeration system enhanced with ejectors

The utilization of ejectors in transcritical CO2 refrigeration systems is known to enhance system performance significantly. However, the operational conditions play a crucial role in determining the system’s overall efficiency. This study introduces a thermodynamic model for transcritical CO2 ejector refrigeration systems and investigates the influence of operating conditions on system performance for four different refrigeration systems, and the optimization of the Nakagawa sound velocity model coefficient in the ejector modeling is carried out to enhance the accuracy of the model. Meanwhile, these research contents are also the innovation of the research. Key conclusions include: (1) Increasing the Nakagawa coefficient to 1.1 improves model accuracy. (2) Ejector inclusion enhances system COP, with one configuration showing a 43.36 % increase and another a 53.23 % increase, recommending different system setups for large spaces like supermarkets and smaller areas like refrigerated vehicles. (3) Higher evaporating pressures result in better COP for ejector systems, with a suggested maximum air cooler pressure of 9 MPa. COP also benefits from increased ejector outlet pressures. (4) AR (area ratio) of the ejector affects mass flow rates and cooling capacity significantly, while its impact on COP is minimal. Adjusting the primary throat area can control cooling capacity for varied needs. The study provides actionable insights for improving the design and efficiency of transcritical CO2 ejector refrigeration systems.

Near-infrared imaging of heat transfer behavior between gadolinium and fluid during magnetization/demagnetization process of magnetocaloric effect

This paper reports on the application of a near-infrared (NIR) imaging system for visualizing heat transfer dynamics from a bulk gadolinium (Gd) sample to the surrounding water during the magnetization/demagnetization process of the magnetocaloric effect (MCE). The suggested approach relied on the spectral variation in water absorption band at 1150 nm wavelength within the NIR spectrum. An experimental setup integrated a telecentric uniform-illumination system, a halogen lamp, and an NIR camera to enable real-time monitoring of a single magnetization and demagnetization cycle induced by an external magnetic field, which was generated by a permanent-magnet-based magnetic circuit. Two-dimensional absorbance images captured during this cycle clearly depicted the thermal energy generated by the MCE in water. Furthermore, an analysis of the thermal boundary layer and the quantification of heat transfer from Gd to water provided insights into the dynamics over time. These results indicated the potential of our NIR imaging techniques in optimizing thermal–fluid interactions within MCE systems, thereby improving the design and efficiency of magnetic refrigeration systems.

Condensation Flow of Refrigerants Inside Mini and Microchannels: A Review

Nowadays, the demand for obtaining high heat flux values in small volumes has increased with the development of technology. Condensing flow inside mini- and microchannels has been becoming a promising solution for refrigeration, HVAC, air-conditioning, heat pumps, heat pipes, and electronic cooling applications. In these applications, employing mini/microchannels in the condenser design results in the working fluid, generally refrigerant, undergoing a phase change inside the mini/microchannels. On the other hand, the reduction in the hydraulic diameter during condensation gives rise to different flow regimes and heat transfer mechanisms in the mini- and microchannels compared to the conventional channels. Therefore, the understanding of fluid flow and heat transfer characteristics during condensation of refrigerant inside mini- and microchannels has been gaining importance in terms of condenser design. This study presents a state-of-the-art review of condensation studies on refrigerants inside mini- and microchannels. The review includes experimental studies as well as correlation models, which are developed to predict condensation heat transfer coefficients and pressure drop. The refrigerant type, thermodynamical performance, and compatibility, as well as the environmental effects of refrigerant, play a decisive role in the design of refrigeration systems. Therefore, the environmental impacts of refrigerants and current regulations against them are also discussed in the present review.

Study on characteristics of wet compression-absorption refrigeration cycle with CO2-ionic liquid mixture

The novel wet compression-absorption (WCA) refrigeration cycle with CO2-ionic liquid mixture can bring a new solution for the development and promotion of CO2 in the refrigeration field, but the depressurization mechanism of this cycle still needs further research. Based on the vapor-liquid equilibrium data of CO2-[emim][Tf2N] mixture, the p-h diagrams of CO2-[emim][Tf2N] mixture with the specific global CO2 mole fraction were first calculated and constructed. The cycle flow of WCA refrigeration cycle with CO2-[emim][Tf2N] mixture was plotted on the diagram, the cycle characteristics and depressurization mechanisms of this cycle were analyzed. The results show that there is a temperature slip in the CO2-ionic liquid mixture during the absorption/desorption process. Both strengthening the effectiveness of cooling measures and increasing the proportion of ionic liquid in the mixture can further reduce the operating pressure at the high-pressure side, but the latter may cause a reduction in the cycle refrigeration performance and energy efficiency. For the WCA refrigeration cycle with CO2-ionic liquid mixture, it is crucial to equip an internal heat exchanger, which can significantly improve the corresponding refrigeration capacity and energy efficiency. This study can provide important references for the design and optimization of WCA refrigeration system using a CO2-ionic liquid mixture.

Effect of Perforated Metal Shield in the Operation of a Marine Refrigeration System with Waste Heat Recovery Channel

This paper presents an improved design of a marine refrigeration system using a perforated metal shield (PMS). The PMS helps in the sustainability of the operation of the system amidst the windy condition in the middle of the sea. This improved design reached the highest value of the coefficient of performance (COP) of the refrigeration system which is 3.51 at -2°C evaporating temperature. The target temperature of the product stored in the refrigeration system is also achieved.

Design and Fabrication of a LiBr Absorption Refrigeration System to Utilize the Waste Heat of Engine Exhaust Gas for Vehicle Cabin Cooling Application

Design and Fabrication of a LiBr Absorption Refrigeration System to Utilize the Waste Heat of Engine Exhaust Gas for Vehicle Cabin Cooling Application

Proposal and evaluation of a combined refrigeration system for engine waste heat recovery based on a supercritical CO2 Brayton cycle

Abstract In recent years, engine waste heat utilization technology has become one of the essential directions for green energy-saving development. In this study, the design of a combined refrigeration system for engine waste heat recovery under a two-stage supercritical carbon dioxide Brayton cycle is carried out, and based on the engine top-cycle energy flow and reactive flow characteristics, combined with thermodynamic and economic analysis models, the thermal and reactive efficiencies of the S-CO_2 Brayton cycle system are investigated. The multi-objective optimization model for waste heat recovery was created with hydropower efficiency and investment return as its objectives. The results showed that the minimum values of annual operating cost and initial investment cost of the combined system under the optimized conditions were 104.8 and 505.2 thousand RMB, respectively, and the total system energy loss was 7.25%. By further analyzing the top cycle parameters of the combined system, it is concluded that the combined system has better thermo-economic performance, and the results can provide some references for the combined refrigeration with engine waste heat recovery.

Ultra-Low-Temperature Refrigeration Systems: A Review and Performance Comparison of Refrigerants and Configurations

During the last decade, many industrial and medical applications have shown a requirement for low-temperature-cooling usage (from −40 to −80 °C), which cannot be efficiently obtained via the conventional refrigeration systems usually employed for medium-temperature applications (from 0 to −40 °C). A proper ultra-low-temperature (ULT) refrigeration system design is essential to achieve the desired output. The performance can be maximised via the suitable selection of the configuration and refrigerant for a specific temperature range. This work contributes a detailed overview of the different systems and refrigerants used in ultra-low-temperature applications. Different systems, such as single-stage vapour compression, multi-stage, cascade, auto-cascade, and air refrigeration cycles, are presented and discussed. An energy analysis is then carried out for these systems identifying the optimal system design and refrigerant selection to achieve the highest performance. This paper aims to provide the reader with a comprehensive background through an exhaustive review of refrigeration systems suitable for ultra-low-temperature applications. The effectiveness of these systems is proven numerically, mainly based on the temperature level and purpose of the application.

Experimental validation of the theoretical ejector model in a low-grade waste heat refrigeration system using R1233zdE as a working fluid

Rising electricity prices and environmental regulations make it increasingly economically justifiable to utilize low-temperature waste heat, generated as a by-product of many technological processes. One potential application is the conversion of heat into cooling capacity using an ejector refrigeration system, to replace conventional electric-consuming cooling systems. Such systems, despite numerous descriptions in the literature, have not found industrial applications up to date. This work presents experimental results on the first commercial prototype cooling system driven by 200 kW waste heat of ultra-low temperature between 60 °C and 70 °C coming from the oil system of air compressors operating under real industrial operating conditions. A refrigeration system configuration based on the use of heat recovery downstream of the ejector and splitting the waste heat recovery heat exchanger into two stages was applied. The low GWP and low-pressure HFO R1233zd(E) refrigerant was used as a working fluid. The high-temperature cooling parameters, equivalent to the glycol temperature of 16 °C/19 °C (outlet/inlet of the evaporator), were examined and the COP of 0,25 was obtained. To obtain such a promising COP value, the critical and subcritical parameters of the ejector were investigated. Based on the experimental results the validation of the ejector theoretical model was performed for low-pressure refrigerant. The ejector component characteristic efficiencies were optimized for the ejector calculation model, and ejector key performance parameters were estimated to a high accuracy. The average relative error in the estimation was 7.1%, 4.5%, and 13.7% for the mass entrainment ratio, pressure ratio and ejector total efficiency, respectively. The resulting accuracy is sufficient from the perspective of refrigeration system design.

Design and Building of a Two-Stage Cascade Refrigeration System for Storage of Blood Plasma

Daily life-saving transfusions rely on the usage of blood products in clinical and research settings. With its proteins used for replacement treatment, human blood plasma serves as the main source for a variety of therapeutic transfusions. During the COVID-19 pandemic, plasma-based therapy was one of the treatment modalities used to treat infectious infections and as a source of neutralizing antibodies in patients. The specialty of transfusion medicine was adversely impacted and faced a stockpile shortage because plasma must be quickly frozen within six hours of collection in order for its proteins and coagulation components to be of the optimum quality. As a result, the cascade refrigeration system is an innovative technology that can provide the required ultra-low freezing temperature and maintain the same temperature in storage for plasma management. The paper concentrated on the design and construction analysis of a two-stage cascade refrigeration system for quick freezing time, and storing plasma proteins at extremely low temperatures to prolong their limited shelf life in a sensitive, temperature-controlled storage system. The choice of refrigerants R404A and R410A is made for high temperature and low temperature circuits which are carefully selected based on study and analysis of the characteristics of different refrigerants for short-term freezing. The ultra-low temperature evaporator is achieved using a blend of two vapour compression refrigeration cycles thermally connected by a heat exchanger to produce a freezing temperature of -35 0C. For analysis, the system was charged with various weights of plasma weighing between 1 kg and 4 kg for two hours and a half hour and kept at a temperature of -35 0C. The system's dependability and practicality for extending plasma shelf life were assessed. After 72 hours of temperature-controlled storage, the results showed 75% efficiency and a negligible (0.4) plasma quality drop.

Design and Fabrication of Solar-Powered Portable Thermoelectric Refrigeration System for Thermolabile Pharmaceuticals

Abstract: In order to maintain the therapeutic efficacy of thermolabile medicine and vaccines, electrical energy must be continuously supplied. For remote areas lacking access to electrical electricity, this poses a serious dilemma. The potency level of thermolabile medications and vaccines is decreased, particularly during last-mile delivery, which causes significant financial loss. In this study, we designed and developed a portable active refrigeration system that runs on solar photovoltaic cells for the refrigeration of thermolabile pharmaceuticals to be utilized in rural areas without access to electricity, especially to facilitate last-mile vaccination delivery. The system makes use of a thermoelectric refrigeration system that, when given electrical power, causes a temperature difference based on the Peltier effect. It will be demonstrated that a solar panel with a peak power of roughly 50W and batteries with a storage capacity of 10Ah are needed for a typical application for vaccine refrigeration. The developed refrigeration system has a 3-liter volume capacity and can store 150 vaccine ampules, each with a 10ml capacity, at temperatures between 2°C to 8°C using a Peltier cell (TEC), that consumes 66 W at 12V

Investigation on solid-liquid equilibrium for binary mixtures of carbon dioxide (R744) and alkanes: Propane (R290) and isobutane (R600a)

The solid-liquid equilibrium (SLE) of binary systems containing carbon dioxide (R744) and alkanes propane (R290) and isobutane (R600a) was experimentally investigated. A novel experimental setup using the cooling curve method was designed, built and verified, enabling SLE measurements at temperatures down to 173 K. The temperature and pressure of the triple point of carbon dioxide (CO2) were measured. The results for R744 and the binary mixture of carbon dioxide and propane were in agreement with the available literature data, demonstrating the accuracy of the experimental setup. Activity coefficients were determined for the binary mixtures studied. The Schröder and Wilson equations were used to calculate solubility over various temperatures and compositions. The Wilson model produced a very accurate correlation for the studied non-ideal binary mixtures, while the Schröder equation did not provide satisfactory results. Determined activity coefficients and SLE curves should be useful for the design of low-temperature refrigeration systems operating on carbon dioxide mixtures with low global warming potential.

Novel memetic of beluga whale optimization with self-adaptive exploration–exploitation balance for global optimization and engineering problems

A population-based optimizer called beluga whale optimization (BWO) depicts behavioral patterns of water aerobics, foraging, and diving whales. BWO runs effectively, nevertheless it retains numerous of deficiencies that has to be strengthened. Premature convergence and a disparity between exploitation and exploration are some of these challenges. Furthermore, the absence of a transfer parameter in the typical BWO when moving from the exploration phase to the exploitation phase has a direct impact on the algorithm’s performance. This work proposes a novel modified BWO (mBWO) optimizer that incorporates an elite evolution strategy, a randomization control factor, and a transition factor between exploitation and exploitation. The elite strategy preserves the top candidates for the subsequent generation so it helps generate effective solutions with meaningful differences between them to prevent settling into local maxima. The elite random mutation improves the search strategy and offers a more crucial exploration ability that prevents stagnation in the local optimum. The mBWO incorporates a controlling factor to direct the algorithm away from the local optima region during the randomization phase of the BWO. Gaussian local mutation (GM) acts on the initial position vector to produce a new location. Because of this, the majority of altered operators are scattered close to the original position, which is comparable to carrying out a local search in a small region. The original method can now depart the local optimal zone because to this modification, which also increases the optimizer’s optimization precision control randomization traverses the search space using random placements, which can lead to stagnation in the local optimal zone. Transition factor (TF) phase are used to make the transitions of the agents from exploration to exploitation gradually concerning the amount of time required. The mBWO undergoes comparison to the original BWO and 10 additional optimizers using 29 CEC2017 functions. Eight engineering problems are addressed by mBWO, involving the design of welded beams, three-bar trusses, tension/compression springs, speed reducers, the best design of industrial refrigeration systems, pressure vessel design challenges, cantilever beam designs, and multi-product batch plants. In both constrained and unconstrained settings, the results of mBWO preformed superior to those of other methods.

Heterogeneous differential evolution particle swarm optimization with local search

To develop a high performance and widely applicable particle swarm optimization (PSO) algorithm, a heterogeneous differential evolution particle swarm optimization (HeDE-PSO) is proposed in this study. HeDE-PSO adopts two differential evolution (DE) mutants to construct different characteristics of learning exemplars for PSO, one DE mutant is for enhancing exploration and the other is for enhance exploitation. To further improve search accuracy in the late stage of optimization, the BFGS (Broyden–Fletcher–Goldfarb–Shanno) local search is employed. To assess the performance of HeDE-PSO, it is tested on the CEC2017 test suite and the industrial refrigeration system design problem. The test results are compared with seven recent PSO algorithms, JADE (adaptive differential evolution with optional external archive) and four meta-heuristics. The comparison results show that with two DE mutants to construct learning exemplars, HeDE-PSO can balance exploration and exploitation and obtains strong adaptability on different kinds of optimization problems. On 10-dimensional functions and 30-dimensional functions, HeDE-PSO is only outperformed by the most competitive PSO algorithm on seven and six functions, respectively. HeDE-PSO obtains the best performance on sixteen 10-dimensional functions and seventeen-30 dimensional functions. Moreover, HeDE-PSO outperforms other compared PSO algorithms on the industrial refrigeration system design problem.

Experimental investigations on the performance of a thermo-mechanical refrigeration system utilizing ultra-low temperature waste heat sources

Experimental studies that investigate the utilization of ultra-low temperature (between 48 °C and 120 °C) waste heat, which forms 25 % of the global unrecovered waste heat, to drive thermal cooling systems are rare. Thus, this study fills a significant gap in the literature by (i) experimentally evaluating the performance of a new full-scale thermo-mechanical refrigeration (TMR) system at ultra-low temperatures ranging from 50 °C to 85 °C, (ii) characterizing its operation with different commercial refrigerants, and (iii) identifying optimal operating conditions and working fluids for the investigated TMR system. An organic Rankine cycle (ORC), vapor compression cycle (VCC), and expander-compressor unit (ECU) make up the TMR system. To ensure its efficient operation, flexibility, and reliability, a full-scale ECU-based TMR system with a design capacity of 1 kW at a heat source temperature of 85 °C is built and put through a series of tests. Furthermore, the TMR system is tested with different commercial refrigerants (R134a, R410A, R407C) over a wide range of operating conditions of the power loop. The results reveal that the ECU-based TMR system can work with ultra-low temperatures of 65 °C with an energy efficiency of 5.92 % and COP of 2.36, for the ORC and VCC, respectively. At a heat source temperature of 85 °C, a condenser water temperature of 15 °C, and an evaporator water temperature of 33 °C, the energy efficiency of the ORC and COP of the VCC are increased to 9.85 % and 3.99, respectively. For the cooling quality, the TMR system shows a minimum evaporator temperature of −10 °C using R134a in both the power and cooling loop, which is improved to lower than −20 °C by using R407C in the cooling loop. The results presented herein will be beneficial to the development, design, and optimization of refrigeration and power systems that utilize low-temperature waste heat.

Analysis and Research of Compound Refrigeration based on Logic Control Battery

In order to ensure the safety and stability of the power battery, the design of refrigeration system is very important. Firstly, a battery model based on logic control and lumped heat parameters was established to determine the real-time and accurate state of battery heat generation, heat transfer, radiation heat dissipation and battery temperature. The feasibility of the simulation model is verified by the experimental results. Secondly, the refrigeration system of battery air cooling and liquid cooling is established, and a new composite cooling system is proposed and built. By changing the wind speed and flow rate, the variation of the cooling effect of air cooling and liquid cooling with the medium flow rate was analyzed. The results show that, in a certain range, the larger the flow rate, the more obvious the cooling effect of the cooling method, and the flow rate is positively correlated with the cooling effect. In order to compare the cooling effect of the new composite cooling system, the temperature rise curves, temperature difference curves and energy consumption of different cooling methods were analyzed under the discharge rates of 4C and 8C.he results show that when the system tends to be stable, the total energy consumption of liquid cooling and mixed cooling is almost the same, and the energy consumption of air cooling is the largest. According to the analysis of the maximum equilibrium temperature difference inside the battery unit when the temperature is stable, the temperature difference of the composite cooling method is the smallest, about 1℃. Moreover, by analyzing the fluctuation range of battery pack temperature when it is stable, the fluctuation of composite refrigeration is the smallest, only 2℃. In conclusion, the hybrid refrigeration system based on logic control has good cooling performance.

Water Conditioning Refrigeration System Design and Construction for Lobster Cultivation

This research is to determine the cooling burden of the water conditioning system for lobster conditioning, where water must be conditioned to its temperature by its 21°C conditioning. This device uses steam compression systems precisely by utilizing water conditioning systems to condition water to stay awake at a temperature of 21°C. The method used in this study was to determine the volume of the water tank and its cooling capacity by calculating the load load and calculating the heat load through the walls of the water tank and other heat generated. For lobster cultivation, an air conditioning machine with a capacity of 1/2 PK. From the results of testing the tool for 3 hours, the results of system performance at an evaporation temperature of 15.2 °C and a product temperature of 21 °C obtained a Carnot COP of 7.11, an actual COP of 5.87, and an efficiency of 82.55%. This is in accordance with Design Carnot COP 8, actual COP design of 6.7, and design efficiency of 83%.

Case study: Design of an absorption refrigeration system for milk preservation in Jalisco, Mexico

This article presents a case study focused on designing a refrigeration system for milk storage in a town of Jalisco, Mexico. An absorption refrigeration unit is proposed, activated with a geothermal heat source from an existing well. An economic analysis of the proposal and its comparison with a conventional system and a solar system is presented. The proposed system must provide refrigeration to the warehouse (cold room) with a cooling load of 5 kW, with a geothermal heat source temperature of 80 °C for the single effect system and 163 °C for the double effect system. For the design of the warehouse, the thermal loads were obtained through ceilings and walls, by lighting, infiltration, and by occupation, through the EnergyPlus software. The results show values of monthly thermal loads ranging between 0.94 and 1.1 kW. The single-effect system achieved a COP of 0.85 costing approximately $13,083, while the double-effect system reached a COP of 1.38 with a cost of $18,144.

Seasonal performance and climatic adaptability of a solar-powered microchannel membrane-based absorption refrigeration system

Microchannel membrane-based absorption refrigeration system (MMARS) has vast potential to satisfy the increasing cooling demand by utilizing renewable and waste thermal energy. To maximize its potential for future large-scale applications, the geometries of the MMARS were optimized for the first time to obtain the lowest system cost under various weather conditions and cooling demands in different climate zones of China. After optimization, Kunming (mild region) has the highest levelized cooling demand cost of 0.2710 $/kWh because of its high initial cost, while Beijing (cold region) has the lowest cost of 0.1508 $/kWh due to its rich solar energy to reduce the operating cost and sufficient cooling demand to levelize the initial cost. It is worth noting that if only natural gas is counted in energy consumption, Kunming, with rich solar energy, achieves the highest seasonal COP of 2.654, but Hong Kong (hot summer and warm winter region) with insufficient solar energy only gets 1.318 because of the low proportion (48.84%) of solar energy in its heat sources. This paper provides a seasonal performance-based geometries optimization of the MMARS and studies its climatic adaptability in different climate zones, facilitating the reasonable design and application of efficient and compact absorption refrigeration systems.

Integrated Design of a Supermarket Refrigeration System by Means of Experimental Design Adapted to Computational Problems

In this paper, an integrated design of a supermarket refrigeration system has been used to obtain a process with better operability. It is formulated as a multi-objective optimization problem where control performance is evaluated by six indices and the design variables are the number and discrete power of each compressor to be installed. The functional dependence between design and performance is unknown, and therefore the optimal configuration must be obtained through a computational experimentation. This work has a double objective: to adapt the surface response methodology (SRM) to optimize problems without experimental variability as are the computational ones and show the advantage of considering the integrated design. In the SRM framework, the problem is stated as a mixture design with constraints and a synergistic cubic model where a D-optimal design is applied to perform the experiments. Finally, the multi-objective problem is reduced to a single objective one by means of a desirability function. The optimal configuration of the power distribution of the three compressors, in percentage, is (50,20,20). This solution has an excellent behaviour with respect to the six indices proposed, with a significant reduction in time oscillations of controlled variables and power consumption compared with other possible power distributions.