ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Flow Boiling Heat Transfer in Small Cross Section Area Tubes with R134a and R32
要約
In this study, the characteristics of local heat transfer coefficient (HTC) and pressure drop are experimentally
investigated in a multiport aluminium tube at low vapour qualities. The tube consists in 18 parallel triangular
channels and hydraulic diameter of 0.715 mm. Two refrigerants of medium (R134a) and high (R32) reduced
pressure are used as working fluids. The experimental ranges studied include: mass velocity [275−1230]
kg·m−2s−1, heat flux [0.98−9.30] kWm−2, saturation temperature [285.65, 280.65, 278.15] K and vapour quality [0−0.55]. The flow boiling results indicated that the local HTC is strongly influenced by heat flux, and it is slightly affected by saturation temperature. Experimental HTC data are compared with six well-known
micro/mini-channel predicting models; the comparisons show that "three zone flow boiling model" proposed
by Thome et al. estimates quite well the experimental local HTC data of R134a, but none of the evaluated
models estimate the flow boiling data of R32 with reasonable accuracy.