Compression Refrigeration System Research Articles

A comprehensive parametric and structural bond analysis of an actual vapor compression refrigeration system with dedicated mechanical subcooled system

A comprehensive parametric and structural bond analysis of an actual vapor compression refrigeration system with dedicated mechanical subcooled system

Thermodynamic analysis of a cascade vapour compression refrigeration system integrated Linde-Hampson cycle

Thermodynamic analysis of a cascade vapour compression refrigeration system integrated Linde-Hampson cycle

Performance analysis of an air compression refrigeration system for data center cooling

An air compression refrigeration performance calculation model applied to data center cooling was established, which is a reverse Brayton cycle system, the operation performance was studied by numerical simulation and the influence of supply air temperature, ambient temperature, pressure ratio, data center room temperature was analysed. The results showed that when the pressure ratio of the air compressor is 1.3, the system obtains the maximum cooling COP; heat exchanger efficiency have a significant effect on the cooling capacity and cooling COP, the efficiency of the heat exchanger increases from 0.6 to 0.8, and the increase in cooling capacity is 4.84 kJ/kg, cooling COP increased by 23.2%; Compared to conventional vapour compression/loop heat pipe natural cooling systems, in cold regions, the annual energy efficiency of air compression refrigeration can reach to 13.85.

Performance Analysis of Multi-Pressure Refrigeration System Using R12, R134 & R22 Refrigerant

Three evaporators having their capillary for expansion in vapour compression refrigeration systems have been considered for experimentation where a single compressor having a single condenser is used. A hand-operated valve is used for controlling the mass flow rate. Refrigerant R-12, R134 and R-22 have been used to check the performance of multiple VC systems for different conditions, where it was found that the performance of R22 is much better than R12 and R134. At present R22 is not used because of its chemical composition which can create problems for the ozone layer in the long term but replacement of R22 is available today with the R400 series. By using this type of system one evaporator can be used as a deep freezer, one evaporator as a frost-free and the other can be used as a normal refrigerator. A compressor with a capacity of 1.0 Tonnes is used. The heavy condenser is used which is generally used in air conditioning systems. The cooling capacity of each evaporator is controlled by an input valve provided, while the compressor and condenser use single-input, single-output point. This appliance has three compartments each having a common access door. The first evaporator is for the first compartment operating at the first pressure level, the second evaporator is for the second compartment operating at the second pressure level and the third evaporator is for the third compartment operating at the third pressure level. By changing the mass flow rate of each evaporator, we can produce different temperatures in each evaporator.

Evaluation of the performance of using R410A and R463A in a vapor compression refrigeration system: Energetic-exergetic analysis and Environmental Impact Index (EII) assessmen

Evaluation of the performance of using R410A and R463A in a vapor compression refrigeration system: Energetic-exergetic analysis and Environmental Impact Index (EII) assessmen

INVESTIGATIONS ON OPEN-CELL METAL FOAM–FITTED TUBES FOR HEAT TRANSFER ENHANCEMENT – A DISCUSSION ON ENHANCEMENT MECHANISMS

Metal foams are drawing increasing attention due to their high surface area-to-volume ratio, high thermal conductivity, and low density. Heat exchanger manufacturers are constantly looking for innovative methods toward building highly efficient and compact heat exchangers. To enhance heat transfer, the effective thermal conductivity, fitment of foam on pipe, influence of working fluids, and effect of the bonding method are major areas of investigation. This paper aims to present a review of various investigations conducted on open-cell metal foam for enhancing heat transfer. The pore size distribution of metal foam directly influences the effective thermal conductivity. Recent progress toward bimodal pore size distribution has been reviewed and discussed. There exists a tradeoff between enhancing heat transfer and the corresponding pressure drop. Different configurations of fitting metal foam on pipes, such as fully filled, partially filled, and tubes wrapped with metal foam, are critically reviewed, and their performance is compared. The working fluid and its conditions used with metal foam has tremendous potential toward enhancing heat transfer. The influence of nonrefrigerants, refrigerants, and nanofluids has been presented in this regard. Different bonding methods and their influence on thermal resistance are also reviewed. To date, there is hardly any literature that addresses the performance of metal foam–fitted tubes in condensers and evaporators for vapor compression refrigeration systems. Metal foam-fitted tubes have shown promising results in terms of heat transfer enhancement. The outcome of this review provides insights into further research on the use of metal foam–fitted tubes for refrigeration applications.

Exergy Analysis of a Solar Vapor Compression Refrigeration System Using R1234ze(E) as an Environmentally Friendly Replacement of R134a

Exergy Analysis of a Solar Vapor Compression Refrigeration System Using R1234ze(E) as an Environmentally Friendly Replacement of R134a

Coupled Continuous PID Controllers for the IFAC Benchmark on Vapor Compression Refrigeration on the Behavioural Setting

This paper presents a behavioral-based controllers design, utilizing evolutionary learning of trajectories, applied to the IFAC PID18 benchmark model for a vapor compression refrigeration system. The challenge of tracing both the evaporator outlet temperature (Te,sec,out) and superheat temperature (Tsh) with disturbances and imposed restrictions is addressed. The challenge integrates a preset discrete MIMO control scheme, serving as a basis for comparison with alternative control schemes. The proposed method also allows for direct experimentation on the system, bypassing the need for reference models or mathematical representations. By developing behavioral paths and iteratively adjusting controller variables, satisfactory control objectives are achieved. The evolutionary behavioral approach is tested on the default discrete control scheme and then applied to newly designed coupled continuous PID controllers, which outperform the benchmark strategy. The method is versatile, adaptable to both model-based and data-driven approaches, and offers a direct relationship with the physical system, independent of both its representation and controller structure, thus emulating real-world conditions effectively.

Switching criteria analysis for a condenser moving boundary model

The switching moving boundary (SMB) scheme is widely used for numerical simulation of heat exchangers, especially in vapour compression refrigeration system. The method divides the heat exchanger into up to three zones (superheated vapour, two-phase fluid and subcooled liquid), depending on the operating conditions and treats each as a lumped-parameter system. During transients the number of zones may vary, and suitable switching criteria and related threshold values must be given, for this change to occur. Also, variables for the zones momentarily phased out need to be tracked, to allow smooth operation of the model. In this work, a switching moving boundary model of a brazed plate condenser in counter-flow arrangement is studied to obtain some useful guidelines for the selection of the optimal switching thresholds. It is shown that these values influence both the accuracy and the numerical robustness of the model; moreover an appropriate selection of these parameters may allow the usage of a fixed-step solver, which is more suitable for real-time simulations.

Experimental Analysis of Alternate Refrigerant Mixtures in Refrigeration System

This study focuses on conducting experimental analyses to assess the impact of alternative refrigerant blends within a vapor compression refrigeration system, with the aim of replacing the existing R134a refrigerant. These refrigerant blends are formulated by combining R600a, R1270, and R290 in four distinct mixing ratios. The assessment considers a range of output parameters for these hydrocarbon mixtures, in addition to their environmental implications related to potential global warming and depletion of ozone layer. Based on the comprehensive evaluation of various factors, it has been determined that the refrigerant blends of R290/R600a/R1270 at proportions of 10% R290 / 20% R600a / 70% R1270 by weight and 20% R290 / 20% R600a / 60% R1270 by weight emerge as the most viable alternatives among the tested refrigerant mixing ratios, surpassing R134a in terms of suitability.

A comprehensive energy, exergy, environmental, and economic analysis of dedicated mechanical subcooled vapor compression refrigeration system

A comprehensive energy, exergy, environmental, and economic analysis of dedicated mechanical subcooled vapor compression refrigeration system

Development and experimental study of a compact silica gel-water adsorption chiller for waste heat driven cooling in data centers

In recent years, data centers have experienced rapid construction, leading to a significant surge in energy consumption, and cooling systems have emerged as prominent energy consumers of data centers. Among the cooling technologies, liquid cooling allows higher cooling circuit temperatures and provides potential for heat recovery. As a thermally driven cooling technology, adsorption refrigeration systems offer an alternative way to compression refrigeration systems by utilizing low-grade waste heat from liquid-cooled circuits to produce chilled water for air-cooled components. In this study, a compact silica gel-water adsorption chiller is developed for a small modular data center and experimentally investigated under extremely low driving temperatures. Under the typical summer conditions with the hot/cooling/chilled water inlet temperatures of 50 °C/30 °C/23 °C, the adsorption chiller achieves the cooling power of 4.9 kW and the COP of 0.50. When the cooling water inlet temperature changes from 32 °C to 24 °C, both the cooling power and COP show significant improvements, from 3.04 kW to 10.50 kW and from 0.44 to 0.66, respectively. Moreover, the increase of the hot water inlet temperature from 48 °C to 56 °C can enhance the cooling power to some extent, while the chilled water inlet temperature has little influence on the performance. The experimental results demonstrate the feasibility and performance of the developed adsorption chiller in data center waste heat driven cooling. Besides, potential adsorbents and possible optimization strategies are presented for performance improvement based on adsorption potential method.

Comparative 3E Analysis of Dual-Purpose Compression Refrigeration Systems Operating Under Various Climates in Multi-purpose Cold Storage Facilities

Comparative 3E Analysis of Dual-Purpose Compression Refrigeration Systems Operating Under Various Climates in Multi-purpose Cold Storage Facilities

Experimental investigation on performance enhancement of vapor compression refrigeration (VCR) systems using nanorefrigerant [R-134a + ZrO2] at steady-state

Experimental investigation on performance enhancement of vapor compression refrigeration (VCR) systems using nanorefrigerant [R-134a + ZrO2] at steady-state

Design, simulation, and optimization of portable atmospheric water generator using vapor compression refrigeration system

In this study, the conceptual design and optimization of a portable Atmospheric Water Generator that uses a vapor compression refrigeration system is investigated. The cooling system is needed to decrease the temperature of the ambient air to below its dewpoint. The cooling capacity of the vapor compression refrigeration system was 0.3 kW. The airflow velocity was then varied from 1.5 m/s to 5 m/s with an increment of 0.5 m/s. The diameter of the opening input feed air is 5.7 cm. The ambient air was assumed at 30 °C and 80% of relative humidity as the feed for the system. The results show that the maximum water production was 0.285 L/h which was produced by the air velocity at 2.5 m/s

Performance enhancement and environmental analysis of vapor compression refrigeration system with dedicated mechanical subcooling

The primary focus of this study is on the energy, exergy, and environmental (3E) analysis of a dedicated mechanical subcooled vapor compression refrigeration (DMS-VCR) system for applications involving commercially available water chillers that employ R134a (in both subcooler and main cycle). For a cooling capacity of 100-kW water chillers, the mathematical model of the DMS-VCR system is built to determine the performance parameter of the system. The DMS-VCR system reduces electricity usage by 15.52% and increase in COP by 9.5%, which results in a significant reduction in CO2 emissions of about 15.55%. When compared to equivalent vapor compression refrigeration system (VCRS), the system’s exergetic efficiency is also increased by 8%. Since the computer simulation results will undoubtedly give design engineers a better option, the subcooling and superheating of the vapor compression refrigeration system become alluring in this study. Consequently, the DMS-VCR system performs better as per the combined 3E study.

Performance improvement potential of ejector-based dual-evaporator refrigeration system using photovoltaic modules and nano-refrigerant

This paper presents a novel system for resolving the high energy consumption of conventional vapor compression refrigeration systems. An ejector-based dual-evaporator refrigeration system (EDERS) is developed utilizing photovoltaic (PV) modules and a nano-refrigerant (NR) with 0.5 wt% of Al2O3. This novel arrangement combines four promising environmentally friendly technologies: dual-temperature cycle, ejector, PV panel, and NR. The comprehensive thermodynamic analysis and optimization of the proposed system, energetic and exergetic analysis methods are incorporated to evaluate the performance of nanoparticle (NP)-doped EDERS in this study. The results demonstrate that the use of Al2O3 NP compared with utilizing pure R134a EDERS notably improves performance under typical operating conditions. Specifically, the coefficient of performance (COP), volumetric cooling capacity, and exergy efficiency (ηex) are 7.14 %, 4.33 %, and 8.91 % higher, respectively. Moreover, the compressor power and total exergy destruction are 6.76 % and 9.94 % lower, respectively. Additionally, under the operating conditions considered in this study, the required PV area is reduced by 5.31 %–8.07 %, whereas the COP and ηex values improve by 5.64 %–8.39 % and 5.38 %–10.06 %, respectively. The study also finds that the COP and ηex values of (R600a + Al2O3) surpass those of (R134 + Al2O3), whereas the COP and ηex values of (R1234ze(E) + Al2O3) and (R1234yf + Al2O3) are smaller than those of (R134 + Al2O3). This suggests that the performance benefits of NPs may vary depending on the specific refrigerant used in the system. The results can be employed as a useful guide for the application of NRs to multi-evaporator refrigeration systems before setting up an experimental system.

Study of vapor compression refrigeration system with suspended nanoparticles in the low GWP refrigerant.

The rising global temperatures, attributed to the high global warming potential (GWP) of conventional refrigerants, necessitate the adoption of low-GWP alternatives in HVAC systems. However, these low-GWP refrigerants often exhibit high toxicity and flammability, limiting their usage. To address these challenges, compact heat exchangers incorporating blended refrigerants have been introduced to enhance HVAC system performance. Researchers have also made significant strides in improving HVAC system efficiency by introducing the concept of suspending nanolubricants and nanorefrigerants within the system. This review paper seeks to comprehensively assess the potential of alternative refrigerants containing suspended nanoparticles, commonly referred to as nanorefrigerants. The paper reviews various mechanisms and potential combinations of different nanorefrigerants employed to enhance refrigeration system effectiveness and efficiency. A detailed examination of key heat transfer parameters and the performance predictions of low-GWP refrigerants, including those from the hydrofluoroolefin (HFO) and hydrocarbon (HC) classes, is conducted through energy and exergy analyses. Commercial refrigerants like R-134a, R-290, R-600, R-600a, R-123, R-125, R-22, R-141b, R-152, R-11, R-113, R-404a, R-407c, R-502, R-600a, R-507a, R-1234yf, R-1234ze, 1336mzz(Z), and R-410a are evaluated in conjunction with suspended nanoparticles, considering their specific properties. The findings indicate that the utilization of nanorefrigerants leads to notable improvements in overall system performance, characterized by reduced compressor workloads and increased heat transfer rates. Consequently, the integration of blended nanoparticles into refrigerants holds significant promise for advancing the HVAC field.

Energy and exergy analysis of vapour compression test rig using R134a blended with GN- MWCNT/POE hybrid nano-lubricants

ABSTRACT The most common refrigeration system is the vapor compression refrigeration (VCR) system for a household refrigerator. The challenges for researchers are to minimize the power consumption of the compressor to improve the performance of the refrigeration system. This study aimed to assess and compare the energy and exergy analysis of VCR systems using multi-walled carbon nanotubes (MWCNT) and graphene nanosheets (GN) based hybrid nano-lubricants. The mass concentrations of each nanoparticle 0.3 g/L, 0.5 g/L, 0.7 g/L, and 0.9 g/L are mixed with 250 ml of polyolester oil (POE) separately and charged with 200 g of R134a refrigerant. Furthermore, the MWCNT and GN nanoparticles are mixed in a 50:50 proportion to prepare the same concentration of hybrid nanoparticles. The properties of refrigerants are obtained with the help of REFPROP 9.1 software. The pull-down time, compressor power, pressure ratio, exergy loss, relative irreversibility (RI), and second law efficiency (SLE) are variables that have been examined. The mass concentration of 0.7 g/L of hybrid nano-lubricants (GN-MWCNT/POE) is found to be optimal. It is noted that the pull-down time, power consumption, and pressure ratio of the refrigerator are lowered by 9.01%, 16.09%, and 5.68% respectively when compared to the pure refrigerant, whereas the actual COP and SLE improved by 11.29% and 8.22% at 0.7 g/L hybrid nano-lubricants. In addition, exergy loss and relative irreversibility are decreased for hybrid nano-lubricants.

Operational stability influenced by lubricant oil charge in the CO2 automotive air conditioning system

In a vapor compression refrigeration system, the oil enhances the efficiency of the compressor but impairs the performance of the heat exchanger. This paper focuses on the experimental study of the influence of oil quantity on the operational stability of CO2 air conditioning system. The operational stability of the system under different oil charge quantity and operating conditions is studied. The experimental results indicate that when the oil circulation rate increases to a certain value, the adjustment of electronic expansion valve (EXV) opening or the compressor speed will cause system fluctuation and the outlet of evaporator gets close to no superheat. The critical oil circulation rate of the experimental system is about 9.2 %. The analysis of the fluctuation shows that it becomes more severe with the increasing of the refrigerant mass flow rate. When the mass flow rate increases from 210 kg∙h − 1 to 250 kg∙h − 1 at 7000 r min−1 of compressor speed, the fluctuation frequency increases from 0.072 Hz to 0.095 Hz. The occurrence of unstable phenomena has remarkable impact on system performance, the maximum difference of this system in instantaneous cooling capacity and COP during the fluctuation period is respectively 0.5 kW and 0.13.