EXPERIMENTAL APPARATUS FOR THE DETERMINATION OF CONDENSATION HEAT TRANSFER COEFFICIENT FOR R134A AND R600A FLOWING INSIDE VERTICAL AND HORIZONTAL TUBES RESPECTIVELY

Abstract

Determination of condensation heat transfer coefficients for HFC-134a in a 7 mm i.d. vertical smooth copper tube and R600a in a 4 mm i.d. horizontal smooth copper tube are experimentally investigated. The test sections are 1 m long horizontal and 0.5 m long vertical counter flow tube-in-tube heat exchangers with refrigerant flowing in the inner tube and cooling water flowing in the annulus. The experiments are performed at average qualities ranging between 0.1-0.99 for the horizontal test section and 0.67-0.99 for the vertical test section. The mass fluxes are ranging between 50-120 kg m(-2)s(-1) and saturation temperatures are between 30-43 degrees C for the horizontal test section, the mass fluxes are around 29 kg m(-2)s(-1) and saturation temperatures are between 30-36 degrees C for the vertical test section. The experimental apparatus are designed to capable of changing the different operating parameters such as mass flow rate and condensation temperature of refrigerant, cooling water temperature, and mass flow rate of cooling water etc and investigate their effect on heat transfer coefficients and pressure drops. The ex-proof diaphragm pump for R600a and the gear pump for R134a are used to circulate the refrigerant in these systems. The detailed description of design and development of the test apparatus, control devices, instrumentation, and the experimental procedure are reported and the study of experimental setups from the available literature survey with the existing ones are compared in this paper. The condensation heat transfer coefficients are obtained for two different test sections with various experimental conditions and compared with some well-known correlations in the literature.