Search

The current study concerns the use of azeotropic mixtures in single-stage vapor compression refrigeration system configurations to determine the effect of entrainment ratio on the coefficient of performance. Three singlestage vapor compression refrigeration system configurations are used. The effects of condenser and evaporator temperatures on the single-stage refrigeration system are investigated. The used azeotropic mixtures are: R1234yf + R290, R1234yf + R152a, R1234yf + R600a, R134a + R290, R134a + R600a and R1270 + R134a. It is shown that the simulations results are in good agreement with the literature. The R1234yf + R290 mixture in refrigeration cycle give the highest coefficient of performance and entrainment ratio. The coefficient of performance (COP) increases with increasing of entrainment ratio. [ABSTRACT FROM AUTHOR]

A new method for predicting the Liquid-Vapor critical point of binary mixture, is presented, which is based in geometrical distances. Actually, the method is based on the minimization of the distance between the experimental and calculated values of the critical temperatures and critical pressures. The SRK and PR equations of state along with classical mixing rules of van der Waals were used as thermodynamic models to calculate the critical point of a given mixture. The proposed method requires that the mixture parameters a, b, and the covolume e = b/v of each equation of state be determined at each iteration by solving the resulting cubic equation. For nine binary mixtures containing: hydrocarbon derivatives, carbon dioxide and alcohols are studied. The AARE of the calculated values is about 0.86% for critical temperature and 2.07% for critical pressure. Good agreements are found between the calculated results and experimental data. The technique is a general purpose one and can be applied in connection with other thermodynamic models. [ABSTRACT FROM AUTHOR]

The critical temperature and critical pressure are two important parameters to characterize a particular fluid. In this paper, we have studied the critical points of 24 binary mixtures containing hydrocarbon derivatives, carbon dioxide and alcohols. Computations were performed using the Heidemann-Khalil method, combined with the following equations of state (Eos): van der Waals (vdW), Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR). The Newton-Raphson method was used to solve a set of nonlinear equations in three independent variables (molar fraction x, temperature T and volume V). Comparisons between predicted and available reference data are given to evaluate the accuracy of the thermodynamic model employed. The average absolute relative error (AARE) of the simulated data was less than 0.2% for critical temperature and 3% for critical pressure. A good agreement has been found between model prediction and reference data. [ABSTRACT FROM AUTHOR]