Boiling heat-transfer coefficient variation for R407C inside horizontal tubes of a refrigerating vapour-compression plant’s shell-and-tube evaporator

The present paper presents experimental results obtained from a refrigerating vapour-compression plant’s shell-and-tube (1–2) evaporator working with R407C. Several tests have been carried out to study the influence of the evaporating pressure and the refrigerant’s mass flow rate on the refrigerant’s boiling heat-transfer coefficient inside horizontal tubes. This work has been performed by analyzing the variations of the evaporator’s overall thermal-resistance, computed using the effectiveness-NTU method, considering the influence of pressure drops and glide at the evaporator, and finally transferring the results and conclusions to the boiling heat-transfer coefficient. It has been observed that the variations of the boiling heat-transfer coefficient show a dependence on the evaporating temperature and the refrigerant’s mass-flow rate, which has been analyzed in the test range.