In the present work, the integral equations method is used to calculate transport properties of polar fluids. For this goal, we use the Stockmayer potential and examine theoretically the thermal conductivity of several REFRIGERANT MIXTURES such as R125+R134a, R125+R32, R125+R152a, R134a+R32, R152a+R32, R134a+R143a, and R125+R143a. We solve numerically the Ornstein-Zernike (OZ) equation using the Hypernetted Chain (HNC) approximation for binary fluid MIXTURES and obtain the pair correlation functions. Finally, the temperature dependence of thermal conductivity is studied using Vesovic-Wakeham method and compared with available results.

In this work an analytical equation of state has been employed to calculate the PVT properties of ternary REFRIGERANT MIXTURES. The theoretical EoS is that of Ihm, Song and Mason, which is based on statistical-mechanical perturbation theory, and the two constants are enthalpy of vaporization DHvap and molar density rnb, both at the normal boiling temperature. The following three temperature dependent parameters are needed to use the EoS: the second virial coefficient, B2(T), an effective van der Waals covolume, b(T), and a scaling factor, a(T). The second virial coefficients are calculated from a correlation based on the heat of vaporization, DHvap, and the liquid density at the normal boiling point, rnb. a(T) and b(T) can also be calculated from second virial coefficients by scaling rules. This procedure predicts liquid densities of ternary MIXTURES at saturated state with a temperature range from 173 K to 373 K and pressure up to  4.0MPa, with very good results.

In this research, artificial neural networks(ANNs) have been used to predict the viscosity of lubricant/REFRIGERANT MIXTURES. Temperature, pressure, molecular weight, the mole fraction of REFRIGERANT, and viscosity of REFRIGERANT are used as input variables and viscosity of REFRIGERANT + lubricant MIXTURES is used as a target. The total number of experimental data point of viscosity that used in this study is 1053 that is trained, validated, and tested with random70%(837 data points), 15% (158 data points), and 15% (158 data points), respectively. The results of the AAD% for the train, validation and test sets of data are 0. 39, 0. 48, and 0. 49, respectively. Therefore, studied ANN models with 15 neurons in a hidden layer are in good agreement with experimental data.

In this study, the intermolecular potential energies of some environment-friendly industrial HFC REFRIGERANTs were obtained through the inversion method based on the corresponding states principle. These potentials were later employed in calculation of transport properties (viscosity, diffusion, thermal conductivity and thermal diffusion factor) of some binary and ternary REFRIGERANT MIXTURES, in the low density region. Predicted transport properties were compared with the available literature data leading to an acceptable agreement. The interaction potential was fitted to an analytical form, and the calculated low density transport properties were also fitted to the fairly exact equations. In the case of R410A and R421B MIXTURES, high density viscosity values were also calculated through the Vesovic-Wakeham method. Due to lack of experimental values on high density viscosities of these two MIXTURES, we could only compare the calculated high density viscosities for other available molar compositions of R124-R134a and R125-R32 binary MIXTURES with literature data, which an acceptable accordance was also observed.

Clathrate hydrate is a new technology to store the cold energy in air conditioning systems. These compounds offer a high cold storage density. The phase change temperature of clathrate hydrates is more than water. On the other hand, these compounds offer better heat transfer properties and improved cyclic stability, compared to eutectic salts. These appropriate properties of clathrate hydrates made these compounds as promising potential for cold storage air conditioning systems. In this study, we investigated the REFRIGERANT hydrate formation as a potential to store the cold energy. The equilibrium data reported by researchers are collected and the effect of various additives on their phase equilibria are investigated. A comparison between the dissociation pressure of hydrate formed in presence of some REFRIGERANT are undertaken. Finally, the various methods of hydrate-based refrigeration systems reported in literature are collected along with their advantages and drawbacks.

In industrial processes, there are many processes that operate below ambient temperature. Usually when these processes demand refrigeration over a very wide temperature range, cascade refrigeration systems are employed. Unfortunately, the cascade refrigeration systems are capital intensive because of major use of installed equipment and large energy requirement in operations. Therefore, the continuing development of new methods to reduce net power and capital costs of refrigeration systems is important in the design of low temperature processes. A recent advancement has been the introduction of MIXTURES as REFRIGERANTs in place of pure REFRIGERANTs. In mixed REFRIGERANT cycles, the composition of the mixture can be selected such that the liquid REFRIGERANT evaporates over a temperature range similar to that of the process cooling demand to provide the desired REFRIGERANT characteristics. Small temperature driving force leads to near-reversible operation, thus better thermodynamic efficiency and lower power requirement. Also, a mixed REFRIGERANT cycles feature simpler machinery configuration and fewer maintenance problems. Due to the lack of comprehensive design method for mixed REFRIGERANT cycle, conventional approaches are largely trial-and-error and therefore operations can be far away from optimal conditions. The difficulty in design mainly stems from two aspects: one is the expensive and highly nonlinear nature of computation and the other is the sensitivity of the cycles to the operating changes, especially the change in the composition of REFRIGERANT MIXTURES and, the suction and discharge pressures of compressor. In this paper, a novel method for comprehensive design of mixed REFRIGERANT cycles is proposed by combined mathematical programming and thermodynamics approach. This method combines the power of thermodynamics and mathematical programming. While the mathematical programming can satisfactorily give the optimal choice of pressures operating conditions and REFRIGERANT compositions, thermodynamics at the same time gives the user insights and confidence in solution. The procedure is demonstrated using a case study of design of two mixed REFRIGERANT cycles for cold section of olefin plant of Tabriz petrochemical complex.

A thermodynamic analysis of a flash/ORC geothermal plant using zeotropic MIXTURES as working fluid is carried out to investigate and improve the performance of the system from the viewpoint of first and second laws of thermodynamic. The MIXTURES of three hydrocarbons (Hexane, Cyclohexane and Isohexane) with two REFRIGERANTs (R245fa and R236ea) are investigated as the working fluid of organic Rankine cycle (ORC). Variation of first and second laws efficiencies, net output power and exergy destruction as a function of the mass fraction of REFRIGERANTs from 0 to 1 is reported. The results showed that the first and second laws efficiencies maximized at a specific value of REFRIGERANT mass fraction. Also, the net power output of ORC shows an optimum amount by changing the REFRIGERANT’ s mass fraction. Furthermore, exergy destruction in evaporator which is the main source of exergy destruction in ORC has its lowest value in the average amounts of REFRIGERANT mass fraction. According to the results, Cyclohexane/R236ea mixture with a ratio of 0. 6/0. 4 represents the best performance from the viewpoint of energy and exergy which leads the system net output power production of 7. 31 MW.

This paper presents environment friendly REFRIGERANT R290 as a solution to the environmental concerns like depletion of ozone layer and rise in global warming because of wide use of synthetic REFRIGERANTs R22 and R134a. The water cooler is the widely used refrigeration application in warm climatic countries. REFRIGERANT R22 and R134a are predominantly used REFRIGERANTs in water cooler refrigeration systems. These REFRIGERANTs are to be phased out as per the international agreements, Kyoto and Montreal protocol. This experimental study investigates the applicability of the environment friendly REFRIGERANT R290 for applications, especially in warm climate sub-tropical and tropical countries like India. A water cooler test facility of a nominal cooling capacity 1. 5 kW is especially designed, developed for R290 and its performance is investigated at different operating conditions. Performance parameters like cooling capacity, discharge gas temperature and coefficient of performance are analyzed. Results showed that compressor energy consumption and discharge gas temperatures are lower for the water cooler refrigeration system. The overall performance of the especially developed system for water cooler application proved that R290 can be a better alternative REFRIGERANT with respect to energy efficiency and greenhouse impact as a replacement to R22 and R134a.

Herein, the application of Carnahan-Starling-vdW-β equation of state (EoS) for 13 REFRIGERANT fluids was investigated. The EoS could predict the saturated liquid densities of these REFRIGERANTs over the temperature range of 100-400 K and pressures from zero up to187 MPa with the average absolute deviations of 2. 66%. The accuracy of Carnahan-Starling-vdW-β EoS in liquid density prediction was also compared with Peng-Robinson EoS and a perturbed hard-sphere-chain EoS. The surface tension and sound velocity of the saturated REFRIGERANTs were also calculated using the Carnahan-Starling-vdW-β EoS within 4. 76% and 5. 66%, respectively. Finally, Carnahan-Starling-vdW-β was employed to predict Joule-Thomson inversion curve for some studied REFRIGERANT fluids.

Air conditioning REFRIGERANT R134a has value of global warming potential (GWP) 1300, which is much higher than MAC Directive (GWP below 150) passed in July 2006. This prompted a search for alternative REFRIGERANT with GWP value less than 150. R1234yf is a new REFRIGERANT which has lower GWP value of 4. Effect of blower speed has been compared and flammability issue of R1234yf has been addressed. Cooling time and relative humidity of car air -conditioning system using REFRIGERANT R134a and R1234yf has also been discussed. The paper discusses various aspects for the replacement of R134a and provides a long term sustainable substitute of presently used REFRIGERANT R134a in automobile air-conditioning.