Hydrocarbon Refrigerant Mixture Research Articles

The Molecular Dynamics Simulation of Thermal Properties of R290 for Auto-cascade Refrigeration System

Background: Hydrocarbons are increasingly being considered as potential fourth-generation refrigerants due to their environmentally-friendly properties. However, accurate prediction and calculation of their thermal properties are essential for their industrial application. Objective: In this study, molecular dynamics simulations were performed to calculate the density, self-diffusion coefficient, viscosity and thermal conductivity of R290 at various operating temperatures of 200-240 K and pressures of 0.15 and 0.20 MPa, and 270-390 K and pressures of 1.5 and 2.0 MPa to verify the feasibility of the methods. Methods: The equilibrium molecular dynamics simulation (EMD) approach was utilised. The soundness of the model and force field were verified by calculating the density of the system during the relaxation phase. In the output stage, the self-diffusion coefficient was calculated using the Einstein relation, while the viscosity and thermal conductivity were calculated using the Green-Kubo method. The simulation results were compared with the NIST data values, and the errors were analysed. Results:  Results: The density simulation results for R290 in the relaxation phase yielded an overall average absolute relative deviation (AARD) value of 3.97%. In the output stage, the simulation results for the transport coefficients of R290 showed AARD values of 7.68%, 6.60% and 11.04% for the self-diffusion coefficient, viscosity, and thermal conductivity, respectively, compared to the NIST data values. Conclusion: These results indicate the feasibility of using molecular dynamics simulations to study the transport properties of hydrocarbon refrigerants. The findings also provide a foundation for future research on hydrocarbon refrigerant mixtures. Patent: The research presented in this work could serve as a valuable reference for future patent applications and technological innovations related to hydrocarbon refrigerants, particularly R290. This includes, but is not limited to, delivery pipelines, connectors, storage containers, control and detection systems, and the preparation and application of R290 and other refrigerant mixtures.

Numerical simulation on shell-side flow pattern transition and heat transfer of non-azeotropic refrigerant mixture

The non-azeotropic hydrocarbon refrigerant mixture flowing across shell-side of spiral wound heat exchanger is widely used in liquefied natural gas production industry. However, the phase-change heat transfer mechanism is still lack of thorough understanding. A numerical model is presented for simulating evaporation heat transfer of non-azeotropic hydrocarbon refrigerant mixture, CH4/C2H6, across multiple spiral wound tubes. Volume of Fluid model (VOF) was used to obtain liquid–vapor interface. The heat and mass transfer rates for each component were given as source terms. Thermophysical properties of the mixture were given using mixing laws in the literature. A flow pattern map was developed based on simulation results. The flow pattern transition and heat transfer were analyzed for the mixture with several component mixing ratios. With increasing vapor quality, pure ethane and methane-ethane mixture appear different flow patterns. The pure ethane has smoother liquid film on the tube wall than the methane-ethane mixture. The increasing of methane promotes the flow pattern transition. With vapor quality of 0.2–0.3, falling film flow transfers to shear flow. Shear flow transfers to spray flow for vapor quality of 0.7–0.8, where the heat transfer coefficient starts to decrease for methane-ethane mixture. For falling film flow, the heat transfer coefficient of pure ethane is higher than the methane-ethane mixture. The outcomes may help spiral wound heat exchanger design and evaluation for liquefied natural gas production.

Enhancement of household refrigerator energy efficiency by studying the effect of refrigerant charge and capillary tube length

Experiments were carried out initially by considering pure R134a and hydrocarbon refrigerant mixtures such as (R290/R600a) (HCM1 44/56, HCM2 50/50, HCM3 54/46, HCM4 64/36, and HCM5 74/26 wt %). Tests are conducted at the atmospheric temperature of 30°C in a domestic refrigerator system. The performance parameters such as pull-down time, desired effect, power consumption, and running cost of the system are to be analysed at different evaporator temperatures, the mass of refrigerant and varying length of capillary tubes. To evaluate the refrigeration effect, Power consumption and COP of the domestic refrigerator at various freezer temperatures (–9°C, –12°C & –15°C) were selected. Results report that out of all the alternative mixtures the amount of energy input was less consumed in the case of HCM1 at a minimal expansion length of 6.3 mm. In the case of HCM5, the least energy was consumed at a capillary length of 5.24 mm whereas in the case of R134a it was at 3.3 mm.

A Comparative Study of Multiple Regression and Artificial Neural Network models for a domestic refrigeration system with a hydrocarbon refrigerant mixtures

Abstract Present paper discus with the development models such as Multiple Regression Analysis (MRA) and Artificial Neural Networks (ANN) for a domestic refrigeration system to predict the performance of a system using Hydrocarbon Refrigerant Mixtures (HCRM). The experiments conducted with the changing evaporator temperature (Te), different hydrocarbon refrigerant mass (mr), and variation in capillary tube length (Lc). The ANN model working with the feed backward back-propagation and Levenberg-Marquardt training algorithm is used to develop the model. This model is used to predict the performance considerations such as power consumption, refrigeration effect and COP. Similarly to develop an MRA and it has been checked for adequacy and significance. Finally, the ANN model is an excellent agreement to a multiple regression model with the coefficient of determinations (R2) of 0.989. The minimum correlation coefficient obtained with the ANN method is higher than the maximum correlation coefficient obtained from the MRA. Also, the value of the error of the ANN method is much less than the MRA method indicating the higher confidence coefficient of the ANN. These values indicate that the developed ANN model is more reliable and accurate than the multiple regression analysis. Based on the above study reveals that the ANN approach is a better technique than MRA for performance and prediction of domestic refrigeration system with high accuracy

Influence of Cryogenic Treatment on TiC Nanopowder in R600a and R290 Refrigerant Used in Vapor Compression Refrigeration System

This paper studies the performance of vapor compression refrigeration system using hydrocarbon refrigerant (HCR) mixture (R600a and R290), hydrocarbon nanorefrigerant mixture (R600a and R290/TiC) and cryogenically treated hydrocarbon nanorefrigerant mixture (R600a and R290/Cryo TiC). The COP of HCR (R600a and R290) system is 1.2960, whereas, COP of R600a and R290/TiC nanorefrigerant system is 1.5223. The TiC nanopowder is cryogenically treated at [Formula: see text]C for 24[Formula: see text]h. The treated TiC is dispersed in HCR mixture. Hence, the COP of R600a and R290- Cryo TiC system is further increased to 1.5801. The energy consumption of R600a and R290-TiC is reduced by 10.3% when compared with HCR. Further, it is reduced by 12.69% with respect to cryogenically treated refrigerant (R600a and R290/Cryo TiC) system. The COP is enhanced due to deep cryogenic of TiC nanopowder.

Performance Analysis of Vapour Compression Refrigeration System using HC Refrigerant Mixtures for Water Chiller

The use of HC refrigerant mixtures has been a topic of current research in view of the concerns related to global warming and Ozone depletion problems caused by CFCs and HFCs.. The HC mixture as an alternate refrigerant has been reported to be a promising one in addressing the global warming and Ozone depletion problems. In the present work an experimental set-up is built up to test Vapour Compression Refrigeration (VCR) system with different refrigerants. The aim of this work is to investigate the performance analysis of Vapor Compression Refrigeration system with alternate refrigerants such as Hydrocarbon (HC) refrigerants mixture and compare with Hydro Fluoro Carbon (HFC) refrigerant (R134a) under the similar operating conditions. The alternate refrigerant mixture is selected in the combination of Propane (R290) and Iso-butane (R600a). The refrigeration system variables considered for the investigation of performance are evaporating temperature, condensing temperature and power consumption. The HC refrigerant mixture is observed to give superior performance compared to HFC refrigerant in terms of global warming.

Taguchi Method for Development of Mass Flow Rate Correlation using Hydrocarbon Refrigerant Mixture in Capillary Tube

The capillary tube is an important control device used in small vapor compression refrigeration systems such as window air-conditioners, household refrigerators and freezers. This paper develops a non-dimensional correlation based on the test results of the adiabatic capillary tube for the mass flow rate through the tube using a hydrocarbon refrigerant mixture of 89.3% propane and 10.7% butane (HCM). The Taguchi method, a statistical experimental design approach, was employed. This approach explores the economic benefit that lies in studies of this nature, where only a small number of experiments are required and yet valid results are obtained. Considering the effects of the capillary tube geometry and the inlet condition of the tube, dimensionless parameters were chosen. The new correlation was also based on the Buckingham Pi theorem. This correlation predicts 86.67% of the present experimental data within a relative deviation of -10% to +10%. The predictions by this correlation were also compared with results in published literature.

Empirical Correlations for Sizing Adiabatic Capillary Tube Using LPG as Refrigerant in Split-Type Air-Conditioner

This paper presents correlations for sizing adiabatic capillary tubes which serves as an expansion device in split-type air-conditioner with LPG, novel hydrocarbon (HC) mixtures of butane (HC600) and propane (HC290) as refrigerant. A homogenous two-phase flow model developed by the authors and also experimental investigation of the Liquified Petroluem Gas (LPG) refrigerant flow in adiabatic capillary tubes were used in this study. The theoretical model was used to assess various percentage compositions of these HC mixtures and validated with the experimental data. For each HC refrigerant mixture, correlations for sizing adiabatic capillary tube which contains the relevant factors, viz. capillary tube inner diameter, inlet pressure, refrigerant mass flow rate, capillary tube surface roughness and capillary tube inlet subcooling was developed. The proposed correlations were compared with the authors measured data and found to be in good agreement. Further validation was made by comparing the mass flow rates predictions of the correlations with experimental data of previous studies and found that these correlations are consistent. The correlations can be used in small vapour compression refrigeration systems working with the HC refrigerant mixtures for practical design and optimization.

Exergy analysis of a domestic refrigerator using eco-friendly R290/R600a refrigerant mixture as an alternative to R134a

The aim of the present work is to bring out an exergy analysis of the hydrocarbon refrigerant mixture of R290/R600a as an alternative to R134a on the performance of a domestic refrigerator which is originally designed to work with R134a. The performance of both refrigerants was evaluated using an exergy analysis. The effects of evaporator temperature on the coefficient of performance (COP), exergy loss, exergic efficiency, and efficiency defect in the four major components of the system for R134a and R290/R600a mixture were experimentally investigated. The results obtained showed that the COP of R290/R600a mixture was improved up to 28.5 % than that of R134a. The highest average exergic efficiency of the system (42.1 %) was obtained using R290/R600a mixture at an evaporator temperature of 263 K (−10 °C). The overall efficiency defect in the refrigeration cycle working with R290/R600a mixture was consistently better than R134a.

Experimental investigation of R290/R600a mixture as an alternative to R134a in a domestic refrigerator

R134a is the most widely used refrigerant in domestic refrigerators. It must be phased out soon according to Kyoto protocol due to its high global warming potential (GWP) of 1300. In the present work, an experimental investigation has been made with hydrocarbon refrigerant mixture (composed of R290 and R600a in the ratio of 45.2:54.8 by weight) as an alternative to R134a in a 200 l single evaporator domestic refrigerator. Continuous running tests were performed under different ambient temperatures (24, 28, 32, 38 and 43 °C), while cycling running (ON/OFF) tests were carried out only at 32 °C ambient temperature. The results showed that the hydrocarbon mixture has lower values of energy consumption; pull down time and ON time ratio by about 11.1%, 11.6% and 13.2%, respectively, with 3.25–3.6% higher coefficient of performance (COP). The discharge temperature of hydrocarbon mixture was found to be 8.5 to 13.4 K lower than that of R134a. The overall performance has proved that the above hydrocarbon refrigerant mixture could be the best long term alternative to phase out R134a.

Improved energy efficiency for HFC134a domestic refrigerator retrofitted with hydrocarbon mixture (HC290/HC600a) as drop-in substitute

In India, more than 80% of the domestic refrigerators utilize HFC134a as refrigerant, due to its excellent thermodynamic and thermo-physical properties. But, HFC134a has a high global warming potential (GWP) of 1300. This paper presents experimental results of an energy-efficient hydrocarbon (HC) mixture consisting of 45% HC290 and 55% HC600a as a drop-in substitute for HFC134a at various mass charges of 40 g, 50 g, 70 g and 90 g in domestic refrigerators. The experiments were carried out in a 165-litre domestic refrigerator using HFC134a with synthetic oil as lubricant. The performance characteristics such as COP, energy consumption, pull-down time and discharge temperature of HC mixture were measured and compared with those of HFC134a. During the experimentation the ambient temperature was maintained at 30 ± 2°C. The results showed that the 70 g mixture has better COP, lower power consumption, lower pull-down time and lower discharge temperature than HFC134a. The miscibility of synthetic oil with HC refrigerant mixture was also found to be good.

Liquid-Phase Thermodynamic Properties for the Binary and Ternary Systems of Propane (1), n-Butane (2), and Isobutane (3)

Experimental thermodynamic property data for hydrocarbon refrigerant mixtures are more important now in order to improve the performance of existing equations of state. In the present paper, liquid-phase PVTx data including bubble points for the binary and ternary systems composed of propane (1), n-butane (2), and isobutane (3) are reported. More than 1000 measurements were made by employing a newly developed vibrating-tube densimeter system with an uncertainty of 0.1 kg·m-3 + 0.024% for density, (3 to 7) mK for temperature, 0.26 kPa + 0.022% for pressure, and 0.1 mol % for composition. The present data contain the first set of experimental PVTx data for the ternary system. The measured data are compared with two available thermodynamic mixture models developed by Lemmon and Jacobsen and Miyamoto and Watanabe. A mixture model applied for a modified Tait equation of state is also presented in this paper.

Performance and heat transfer characteristics of hydrocarbon refrigerants in a heat pump system

Performance of a heat pump system using hydrocarbon refrigerants has been investigated experimentally. Single component hydrocarbon refrigerants (propane, isobutane, butane and propylene) and binary mixtures of propane/isobutane and propane/butane are considered as working fluids in a heat pump system. The heat pump system consists of compressor, condenser, evaporator, and expansion device with auxiliary facilities such as evacuating and charging unit, the secondary heat transfer fluid circulation unit, and several measurement units. Performance of each refrigerant is compared at several compressor speeds and temperature levels of the secondary heat transfer fluid. Coefficient of performance (COP) and cooling/heating capacity of hydrocarbon refrigerants are presented. Experimental results show that some hydrocarbon refrigerants are comparable to R22. Condensation and evaporation heat transfer coefficients of selected refrigerants are obtained from overall conductance measurements for subsections of heat exchangers, and compared with those of R22. It is found that heat transfer is degraded for hydrocarbon refrigerant mixtures due to composition variation with phase change. Empirical correlations to estimate heat transfer coefficients for pure and mixed hydrocarbons are developed, and they show good agreement with experimental data. Some hydrocarbon refrigerants have better performance characteristics than R22.