Two-phase frictional pressure drop and heat transfer coefficients investigation in a plate heat exchanger using R-134-a refrigerant

Abstract

Consulta en la Biblioteca ETSI Industriales (8368)

[EN] This thesis investigates the behaviour of R134-a refrigerant in a compact brazed heat exchanger. The investigation has been divided into two main parts. The first one consists of measuring the pressure drop between the heat exchanger ports. Thereafter, different residual pressure drops such as the pressure drop at the ports, elevation pressure drop and acceleration pressure drop, were subtracted from the entire pressure drop in order to get the experimental frictional pressure drop. Once this experimental pressure drop was calculated, it was compared with those obtained using existing correlations, concluding that the Chisholm's correlations with C parameter equal to 4,67, fits in some flux with an error less than 10%. In the second part, different temperatures at the heat exchanger ports were taken, in order to calculate the experimental flow boiling heat transfer coefficients. Once these data was calculated, it was compared with other existing correlations, resulting in a noticeable difference making difficult to find a reliable conclusion. It seems that Cooper correlation is the one which have the least error. According to the specialized literature consulted, correlations with more weight in nucleate boiling fit better than others.