Refrigerants R22 Research Articles

3-D numerical simulation of forced convection heat transfer in microscale rectangular channels for low GWP refrigerants

This study presents a numerical evaluation of the performance of low Global Warning Potential (GWP) refrigerants R600a, R290, R1270, and R134a in heat dissipation by forced convection in a microchannel heat sink. The heat sink comprises 50 parallel microchannels with a cross-sectional area equal to 123 × 494 [µm2]. The differential equations describing the physical behavior interaction between the refrigerant and the copper matrix are solved using the finite volume method and the SIMPLEC coupling algorithm. The numerical model is used to predict fluid mechanics and heat transfer for single-phase laminar conditions including the friction factor, the Nusselt number and the average wall temperatures, as well as the whole performance of the microchannel heat sink. The accuracy of the numerical model is validated by comparing the performance of R600a with experimental data, resulting in deviations within the range of the uncertainty of each parameter. The evaluation of the performance of different refrigerants reveals that the friction factor and Nusselt number are significantly influenced by the microchannel geometry and thermal conditions, exhibiting unique yet similar trends for different refrigerants. Furthermore, the analysis of the average wall temperature in the microchannels demonstrates that the hydrocarbon-based refrigerants effectively reduce the temperature of the copper matrix compared to R134a, suggesting a superior performance in the dissipation of heat flux under single-phase laminar conditions.

Feasibility of solar-powered air-conditioning system using natural refrigerants

This research focuses on low carbon dioxide alternatives to air-conditioning systems that use sustainable and low-power drives. This detailed research takes into account a 1 t capacity air-conditioning system using several refrigerants based on vapor compression. Natural refrigerants should be used instead of all-synthetic ones due to their environmentally favorable properties. Using the CoolPack software platform, a comparative analysis was conducted, and it was found out that the natural refrigerants R290 and R600a exhibited promising results in terms of heat removal from the evaporator (Q e (kW)), heat removal from the condenser (Q c (kW)), work done by the compressor (W (kW)) and coefficient of performance when fixed temperatures of 10°C for the evaporator and 50°C for the condenser were maintained. For the refrigerant R600a, superheating at the compressor (inlet) suction by 5°C was necessary to maintain the running cycle within a practical working zone. Given that a 1 t vapor compression cycle air-conditioning system based on R290 has a compressor work consumption of 640 W, the motor power input for a single-phase induction motor will be roughly 1000 W. In contrast, direct-current (DC) motors require about 30% less power (770 W) and can be readily driven by solar photovoltaic systems (DC). Thus, by presenting solar thermal (required for R600a) and solar photovoltaic power (DC) applications for the natural refrigerants R290 and R600a, the present work will contribute to a sustainable environment and demonstrate the capabilities of dependable operation with optimal power usage.

A numerical study of the R744 primary cooling system for ATLAS and CMS LHC detectors

A R744 (CO2) refrigeration system has been designed to cool down the Large Hadron Collider (LHC) silicon detectors ATLAS and CMS, located at CERN, Switzerland. The silicon detectors are subjected to high radiation levels. The system is composed of a pri- mary CO2 trans-critical booster vapor compression loop operated with piston compressors, and an oil-free liquid pumped loop on the evaporation side, to preserve the detectors. To ensure the system's reliability, the cooling facility is designed to operate under a parallel operation mode of several modular 70 kW plant units providing evaporation temperature as low as -53 °C. This layout, is also useful in case of components failure and maintenance. A numerical model is developed using a dynamic simulation software Dymola that is based on the open source Modelica modelling language. The simulation results are proven on a first demonstration plant (System A) experimentally to explore the systems control logic and to validate the reliability of the system before it is built on the detectors side. In this paper the models development is explained and the results of the experimental validation of the numerical model are shown.

Thermodynamic analysis of a multiple energy production system based on geothermal energy for commissioning in Canada and optimization by response surface method (RSM)

The thermodynamic analysis of a geothermal-based integrated energy system to produce liquid hydrogen, cooling, hot water, and power was presented in this study. The investigated system consists geothermal subsystems, a modified organic Rankine cycle (ORC), a PEM electrolyzer, and a liquid hydrogen storage source. Different organic fluids including refrigerants R113, R123, and R134a were investigated to increase the system performance. Analysis of organic fluids showed that the best organic fluid is R123 because it helps to increase the performance of the system. The authors employed the Design-Expert software and RSM for optimum results purposes, and the objective functions were chosen to be exergy efficiency (EE) and cost rate (CR). Following introduction of design variables, the mass flow rate of input to the evaporator, the temperature of input to heat recovery vapor generator, turbine efficiency, turbine input temperature, evaporator pinch point temperature, and pump efficiency, their impact on the system's performance were investigated. The optimal values for EE and CR were ultimately found to be 43.91 % and 45.12 $/h, respectively. Also, in this research, seven regions within Canada were investigated for the launch of the proposed system. The studied cities were Victoria, Vancouver, Regina, St. John's, Dawson Creek, Whitehorse, and Port Alberni. Finally, Regina was chosen because of the system's superior performance in electricity production at a reasonable cost in that area. The environmental results showed that the presented energy system in Regina city could help to expand 5 ha of green space by producing electricity at the rate of 4993.03 MWh in one year. The findings indicated that implementing the suggested system in Regina would help prevent 1018.6 tons of CO2/MWh from being emitted into the environment yearly, only by chipping in 24445.9 $/ton of CO2 per year.

Optimal charge amount for semiconductor chiller applying eco-friendly refrigerant R-744

The refrigerants used to cool the heat generated in semiconductor production are Freons, which are now subject to regulation because of their high ozone depletion potential (ODP) and global warming potential (GWP). Therefore, R-744 is considered an eco-friendly refrigerant. This study experimentally analyzed the effect of the refrigerant charge amount based on the temperature discharged after cooling objects when operating a brine chiller using R-744 under subcritical conditions. The results showed that the optimal charge amount in terms of the coefficients of performance (COP) differed from that in terms of the maximum cooling capacity. In case of the apparatus used in this study, the optimal refrigerant charge amount with maximum cooling capacity was estimated at 8.2 kg when the temperature of the cooling object was in the range of −20 °C and −10 °C and at 9.2 kg when the temperature of the cooling object was 0 °C. However, in terms of COP, the optimal refrigerant charge amount was estimated at 8.2 kg when the temperature of the cooling object was in the range of −20 °C and 0 °C. This difference was attributed to the variation in the required evaporation heat capacity with the target temperature of the cooling object.

The effect of refrigerant filling pressure on split AC performance with variations in refrigerant R22, R134A, and R290

R-22 refrigerant has been recognized as a major cause of climate change and ozone layer depletion, leading to increased interest in finding more environmentally friendly alternatives. Two alternatives being considered are R-134a and R-290. The main objective of this research is to compare the Coefficient of Performance (CoP) performance of split ACs using three types of refrigerants, namely R-22, R-134a, and R-290, taking into account the environmental impact and operational efficiency. The research method involved retrofitting a 1 PK split AC which initially used R-22 with three different types of refrigerant as an experiment. The research process includes test equipment design, equipment installation, and feasibility testing before carrying out experimental testing. Tests were carried out with variations in refrigerant charging pressure of 70 psi, 75 psi, 80 psi, 85 psi, and 90 psi. The research results showed that the largest COP was found in the R-290 refrigerant, reaching a value of 0.86 at a filling pressure of 90 Psi. The largest COP value for R-22 was also found at a filling pressure of 90 psi, namely 0.66. Meanwhile, R-134a achieved the highest COP value at a filling pressure of 90 psi, with a value of 0.57 at a variation of refrigerant filling pressure of 90 Psi. In conclusion, this study provides better insight into the efficiency and environmental impact of the three types of refrigerants discussed. It also provides a useful information basis for the selection of suitable refrigerants in split air conditioning systems, with the aim of environmental conservation and achieving optimal performance

Condensation heat transfer performance of R290 in a plate heat exchanger for electric vehicle heat pumps

In the continuous improvement of electric vehicles driving range, a heat pump system with low-global warming potential (GWP) refrigerant is a promising solution. In the present work, the condensation heat transfer coefficient (HTC) and frictional pressure drop (FPD) were experimentally evaluated in an offset strip fins embedded plate heat exchanger (PHE), using an eco-friendly, low-GWP refrigerant R290 as the working fluid. A Modified Wilson Plot Method was used to predict the heat transfer of the coolant side (water/ethylene glycol; 50/50 %). The main focus of the present study revolves around the R290-to-coolant condensation experiment, wherein we analyzed the influence of mass flux (G = 20–50 kg m−2 s−1), heat flux (q = 3–12 kW m−2), and saturation temperature (Tsat = 40–55 °C) on HTC and FPD within the PHE while variable mean vapor quality (xm). According to the results, all experimental conditions were fall in the forced-convection condensation regime. The results state that HTC increases with a rise in q, G, and xm, but decreases with a surge in Tsat. Conversely, FPD increases with a rise in G and xm, and decreases with a escalation in Tsat, while q has no significant impact. Correlations were developed to predict the Nusselt number and friction factor values of R290 with mean absolute errors of 10.6 % and 11.2 %, respectively. These correlations are compared to previous research findings, signifying their efficacy in predicting the heat transfer characteristics of R290 within PHEs.

Thermodynamic Simulation of Cascade Cooling System for Vacuum Freeze Drying

Vacuum freeze drying (VFD) is a drying method carried out at pressures and temperatures below the triple point of water. Drying occurs by sublimation. The results of the VFD method are able to maintain the quality of dry ingredients (taste, colour, nutrient, etc.). To achieve a condition below the triple point of water, it is conditioned so that the pressure is under a partial pressure of 6.11657 mbar at a temperature of 0.01°C. The refrigeration system is simulated using refrigerants R-134a and R-22. The purpose of the simulation is to obtain the optimum system conditions. The variables varied were the saturated temperature of the LTC (Low-Temperature Circuit) evaporator, the saturation temperature of the HTC (High-Temperature Circuit) evaporator, the difference in the temperature of the pinch point between the LTC condenser and the HTC evaporator and the temperature of the HTC condenser. The simulation results are the saturated temperature of the LTC evaporator -30°C, the saturation temperature of the HTC evaporator -15°C, the difference in the temperature of the pinch point between the LTC condenser and the HTC evaporator 10°C and the temperature of the HTC condenser 40°C. The highest Coefficient of Performance (COP) of the cascade cooling system with these parameters is 2.55 using a combination refrigerant R22 in HTC and R134a in LTC.

Performance of Split Air Conditioner with Capillary Pipe Variations with R32 Refrigerant on Ships

Performance of Split Air Conditioner with Capillary Pipe Variations with R32 Refrigerant on Ships

R290 Refrigerant Performance in a Commercial Refrigerator

In this study, we investigated the impact of the environmentally friendly R290 refrigerant, which has a higher Coefficient of Performance (COP), on the operating performance of the cooling system, as an alternative to the commonly used R404A refrigerant, which has a negative effect on global warming. The boundary conditions in the refrigeration cycle were designed to be -10°C evaporation and +45°C condensation, and the performance of the system referenced in the TS EN ISO 23953-2 standard was experimentally compared for both refrigerants. The temperature and energy consumption values of the M-packs, whose location and quantity are specified in the relevant standard, have been evaluated in terms of the cooling performance of the cabinet. As a result of the study, the heat removal performance of the system using R290 fluid in the condenser showed better results compared to R404A. According to the relevant standard, the system using R290 is in the C and D classes in the energy consumption evaluation.

Improving Efficiency of Heat Pump Dryer Using R32 Refrigerant by Nanofluid

Drying process are important in many areas in the agriculture and food sectors, including increasing shelf life, improving transportability by reducing product weight or adding value to products. However, the main problem in the drying process is the relatively high energy consumption. Therefore, the development of energy-saving dryers is necessary. Based on the above reasons, this research aims to study the performance enhancement of heat pump dryers using R32 refrigerant by using heat recovery and nanofluid. The heat that is exhausted from the refrigerant by a heat exchanger. In this work, a Nano titanium dioxide (Ti2O3) was selected. Pork was dried under the conditions of drying temperature of 45, 50 and 55 °C and water flow rate in the heat exchanger at the front of the drying chamber of 2, 3 and 4 L/min. Criteria for evaluating heat pump dryer performance include drying rate, specific moisture extraction rate, specific energy consumption, heat pump dryer performance coefficient compared to heat pump dryers without nanofluid. The results showed that increasing the drying temperature and water flow rate in heat exchanger increased the drying rate, power and specific moisture extraction rate in the heat pump dryer using nanofluid. Whereas, the specific energy consumption was lower than the case without nanofluid. Increasing the drying temperature and the water flow rate in the heat exchanger had relatively little effect on the coefficient of performance (COP) of the heat pump dryer. Moreover, the study found that the coefficient of performance of heat pump dryer with nanofluid was in the range of 4.33 - 4.42.

Effects of Heat Transfer Characteristics of R32 and R1234yf with Al2O3 Nanoparticle through U-Bend Tube Evaporator

This study used the Ansys Fluent® computational fluid dynamics code in conjunction with a volume of fluid multiphase model and phase-change model to analyze the flow boiling evaporation heat transfer coefficient and flow patterns of R32 and R1234yf with Al2O3 nanoparticle through the U-bend tube with a curvature ratio for downward-oriented flow. The volume of fluid (VOF) model was used to follow the patterns at the interface, while the SST k-omega model was used to simulate the gas-liquid flow. This work has been validated by utilizing a R134a refrigerant. Simulations were performed at various mass fluxes, vapor qualities, and temperatures to determine the effects of these variables on heat transfer and frictional pressure decrease in the tube. R1234yf shows much better performance than the other pure refrigerants in terms of heat transfer and vaporization. The addition of nanoparticle Al2O3 with the refrigerants R32 and R1234yf significantly improved the heat transfer coefficient and increased the vapor fraction. The frictional pressure drop increases with increasing mass flux and decreases with increasing vapor quality due to a significant decrease in the liquid film thickness. The heat transfer coefficient, on the other hand, increases with increasing mass flux and decreases with vapor quality up to a point. There are certain changes in the heat transfer coefficient at the bend. After the bend, the frictional pressure drop increased at a higher rate than before the bend, and the vapor fraction increased at a higher rate.

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

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

Performance Air conditioner on retrofitted refrigerant hydrocarbon

Synthetic refrigerants used in air conditioner (AC) are very important in depleting the ozone layer and prohibiting global warming. This has led to the application of R32 and Musicool 22 (MC22) as a substitute for R22 because refrigerant is considered more environmentally friendly. Therefore, this research aimed to compare the performance of applying both R32 and MC22 refrigerants in 1 PK split AC using the coefficient of performance (COP) as the indicator for AC performance and compressor power consumption. MC22 filling mass was varied at 90% (202.14 grams), 100% (224.6 grams), and 110% (247.6 grams) of R32 mass, and condenser inlet temperatures at 28°C, 30°C, 32°C, and 34°C. The results showed that MC22 could be used as a viable alternative to R32 due to the higher refrigeration effect value of 332.36 kJ/kg recorded for refrigerant

Changes in freezing temperature, energy consumption, exergy loss and efficiency, and cooling coefficient of R22 and R404a refrigerants over experimental time

This article is to study the working efficiency of air freezing systems using R22 and R404a refrigerants. The main objective is to determine the loss, exergy efficiency and cooling coefficient (COP) of the freezing refrigeration system using R22 and R404a refrigerants. Theoretically, find the law of change in freezing time, energy consumption for the freezing refrigeration system using R22 and R404a refrigerants, machine running at without load (do not leave ingredients in the freezer when the air temperature in the freezer reaches -45oC), with load (when the product core temperature reaches -18oC) by direct and indirect fluid supply methods and find appropriate fluid supply methods for the system's R22 and R404a of refrigerants two-level compression freezer, at the same time analyze exergy and find the suitable freezing mode for the refrigeration system in freezing conditions at temperatures from -30oC to -45oC, wind speed of 6 m/s.

Experimental Evaluation of Condensation of R32 and R134a over a Plain Tube

The rise in demand for universal energy, combined with environmental concerns, prompted a search for a new technology that was compatible with the existing scenario. Nowadays, most conventional refrigerants are being phased out due to environmental restrictions, which has led to the development of alternative refrigerants. Such newly developed alternative refrigerants need further experimental assessment regarding their thermophysical properties. The current work has experimentally looked at the heat transfer phenomena that occur when the refrigerants R32 and R134a condense over a single horizontal plain tube at saturation temperatures of 40–50 °C, wall sub-cooling temperatures ranging from 3 °C to 11 °C, and heat fluxes of 8–31 kW/m2. The results showed that at a saturation temperature of 40 °C, R32 and R134a have a coefficient of condensation heat transfer about 4.0–9.0% higher than that at saturation temperatures of 45 °C and 50 °C. At the same wall sub-cooling temperature, R32 has a 50–55% higher condensing-side heat transfer coefficient than R134a. The validation of the experimental condensing-side heat transfer coefficient with Nusselt’s model revealed a deviation of ±10%. Further, a modified correlation based on Nusselt’s model predicted the experimental condensing-side heat transfer coefficient with an error band of ±5%.

EN Improving the energy efficiency of refrigeration equipment with a direct sales function

The increased use of refrigerants with low global warming potential GWP over the past decade indicates that manufacturers are already making gradual replacements with refrigerants with reduced environmental impact. Thus, in addition to HFC gas phase-out requirements, most EU countries are pursuing a trend to reduce the energy consumption of refrigeration appliances. Such countries restrict the import of equipment that does not meet the energy efficiency requirements. This paper presents the ecodesign of refrigeration equipment in relation to the requirements of the sales market using the Regulation on Conformity Assessment Procedure. HVAC&R equipment contributes to GHG emissions in two ways: directly through refrigerant leakage or venting, and indirectly through electricity use, the latter accounting for up to two-thirds of GHG emissions. The paper compares the energy and environmental characteristics of refrigerants R404a and R290 in freezer M200V. The experimental results show that the highest COP va­lues in the system for R404a and R290 are 3.02 and 3.19, respectively. Possibilities of complete transition from F-gases to natural analogues with GWP ≈ 0 are shown. At application of R290 its advantages on energy efficiency are obvious - reduction of electric power consumption of freezing chests on 8,9 %, influence on environment R404A – GWP=3260, R290 – GWP=3. The calculation of energy efficiency class for freezing chest was made. To improve energy efficiency, a number of design modifications were made: the density of the thermal insulation material and the compressor were changed. The energy consumption of the modified version at the second climatic class was measured at 1.23 kW/24h, and the energy efficiency coefficient according to the calculation EEI =34.904, which corresponds to the energy efficiency class «C».

Experimental research on off-design characteristics of heat pump water heater using low GWP zeotropic blend

Based on the test setup of instant heat pump water heater (IHPWH), the performances of system operating with zeotropic natural mixture (ZNM) (R744/R290 (12/88)) and system operating with R22 refrigerant were compared under variable entry temperature of heat sink (ETHSK) and variable entry temperature of heat source (ETHSC) conditions, aiming to comprehensively evaluate the replacement potential of ZNM in the IHPWH. The results revealed that ZNM had an obvious alternative advantage, mainly attributed to that system operating with ZNM refrigerant achieved the comparable or markedly superior heating capacity and COP and markedly lower discharge temperature compared to those of system operating with R22 refrigerant under two conditions. The discharge temperature of system operating with ZNM refrigerant was reduced by 5.4~26.7? compared to that of system operating with R22 refrigerant, thus system operating with ZNM refrigerant can produce higher temperature domestic hot water. Compared with those of system operating with R22 refrigerant, both heating capacity and COP of system operating with ZNM refrigerant had markedly different trends with the change of ETHSK, while they had slightly different trends with the change of ETHSC. Compared to the ETHSK, the ETHSC has a more conspicuous impact on the heating capacity, COP and discharge temperature of system operating with ZNM refrigerant.

Performance Evaluation Of Refrigerated Pickup Truck Using Hydrocarbon Refrigerants

HFCs group refrigerants are still widely used in refrigerated pickup trucks. This refrigerant is a synthetic chemical and has a high potential to cause global warming and damage the ozone layer. This study aims to obtain performance data from the use of HCs as refrigerant in refrigerated pickup trucks. The research was conducted experimentally on a pickup truck with a 1500 cc engine capacity. The size of the refrigerated room is 2300 mm long, 1500 mm wide and 1400 mm high. A commercial refrigeration system (C-250e MAX, Thermo King Europe, Belgium). The size of the evaporator, which consists of a cold air supply fan and an intake fan, is 133 mm long, 985 mm wide and 525 mm high. The cooling capacity is 2770 W. The volumetric flow rate of cold air is 1100 m3/hr. The test started at 9 am and the temperature value in a gallon of water was measured for 120 minutes. The results showed that the optimal refrigerant filling was the use of R290 (35%) and R1270 (20%). The value of the coefficient of system performance obtained from the use of the two variations of HCs is 4. Thus, refrigerant HCs R290 and R1270 can replace refrigerant HFCs in refrigerated pickup trucks with refrigerant mass variations of R290 (35%) and R1270 (20%).

PRESSURE EFFECT ON POOL BOILING HEAT TRANSFER CHARACTERISTICS OF HIGH-VOLATILE LIQUIDS WITH STRUCTURED SURFACE

The study of enhancement of the heat transfer during boiling and an increase of the critical heat fluxes (CHF) have a great importance in design of the modern and cost-effective heat transfer devices for thermal management of microelectronics, cryogenics and refrigeration, and the power electrical engineering industry. In this work we present the results of the experimental studies of the heat transfer and CHF during the pool boiling of refrigerants R113, RC318, and dielectric liquid HFE-7100 on a structured surface under saturation conditions in the range of reduced pressures 0.03-0.36. The effect the heat flux and pressure on the boiling heat transfer coefficient was studied. It is shown that the correlation of Yagov predicts with an accuracy of ± 35% the CHF for pool boiling of highly volatile liquids on structured surfaces in a wide range of reduced pressure.