This paper deals with the heat exchange performance prediction of a counter flow double-tube condenser for binary natural refrigerant mixtures (propane/n-butane & propane/i-butane ). The local characteristics of the heat transfer and pressure drop are calculated using a prediction method developed by authors, and the total pressure drop, the overall heat transfer coefficient and the average hea...

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 usin...

In the present study, the condensation and evaporation heat transfer performance of a zeotropic refrigerant mixture (HFC32/HFC125/HFC134a) inside horizontal tubes with smooth, grooved or cross·grooved inner surfaces was investigated experimentally. The cross-gTOoved tube showed the highest heat transfer coefficient for both condensation and evaporation with the zeotropic mixture. Its heat trans...

The errors associated with therModynamic performance calculations are discussed with particular reference to systems with a high oil charge. It is shown that calculations made using published refrigerant data can be very misleading as no account is taken of the oil solubility effects. Pressure-enthalpy charts are presented for refrigerant R12 oil mixtures, for a range of oil concentrations. The...

Numerical simulation is extensively used in heat exchanger design and performance evaluation. While evaluating potential working fluids, pure fluids and fluid mixtures with different component combinations and fractions are compared based on simulation results. Two of the challenges while conducting such studies are the uncertainties of refrigerant properties and the applicability of empirical ...

This paper deals with the investigation of substitutes for R-22 and their heat transfer behaviour in a plate-type evaporator with a falling water film as heat source. Alternatives investigated were R-134a and two new refrigerant mixtures. Measurements on a 3m x 0,5m plate showed a superior performance ofR-134a compared to R-22 and mixtures at equal test conditions and a distinct difference betw...

Solubility data of refrigerant/lubricant mixtures have been modeled with a cubic equation of state. The systems studied are binary mixtures of hydrofluorocarbons (R-32, R-125, R-134a and R-143a) and alkylbenzene oils (viscosity grades 15 and 32). These partially miscible mixtures are well correlated with the present model, which can be used for calculating the pressure-temperature-composition r...

Properties of refrigerant/lubricant mixtures are important for design and reliable operation of vapor compression and absorption refflgeration equipment. £valuatJOn of substitute refrigerants and lubncants tor CFCs and of new working fluids for absorption systems can be enhanced by the availability of rap1d and accurate methods for determimng fluid properties. This paper descnbes new methods fo...

A computer model representing a two-evaporator, two-intercooler refrigerator-freezer opera ting at steady-state with nonazeotropic refrigerant mixtures (CYCLEZ) has been developed at Oak Ridge National Laboratory (ORNL). This model is being used to assess the effects of system desig n and operating parameters on the cycle performance of a refrigerator-freezer designed around the L orenzMeutzner...