ISSN Online: 2377-424X
International Heat Transfer Conference 12
Flow boiling of R134a-Propane mixtures -experiments and CML modeling-
要約
A boiling rig has been build, which is capable of measuring the local heat transfer coefficient and the pressure drop in a horizontal test section. The test section has an inner diameter of 10 mm, it is heated not via
electrical energy dissipation but via condensing ammonia on the outside of the test pipe. Thus a nearly constant
wall temperature boundary condition is given, as in most industrial applications of evaporation. Experimental
results for flow boiling of the refrigerant R134a and mixtures of propane and R134a in horizontal plain tubes
are given. The mass flux ranges between 50 to 400 kg/s/m2, evaporation temperature between −40 ±C and 5 ±C
and a maximum pressure of 2 Mpa. The evaluation procedure of the data is summarized, and these experimental
heat transfer coefficients are compared with calculated values from Steiner and Taborek, (1992). Parallel to the
experimental work some numerical modeling of boiling has been performed using the CML (Coupled Map Lattice)
method. This method is based on a dynamic system with continuous field variables but discrete space and time, in
which local flow dynamics propagate in space by diffusion and flow, while time is advanced by repeated mapping.