Numerical Simulations On Flow Process Of Iso-butane In Non-adiabatic Capillary Tube

In small refrigeration equipment condensation and evaporation, due to temperature big changes in temperature, refrigerating capacity is not large also, in order to simplify the structure, generally by capillary instead of expansion valves as refrigeration system of throttling step-down components. Early in the 1930s, capillary is already applied to the refrigeration system. Almost the same period, back to hot principle is applied to the expansion of the capillary process, formed to throttle thermal capillary, greatly improving the refrigeration system of refrigeration efficiency.This paper starting point has two aspects:environmental factors:atmospheric ozone destruction and greenhouse effect has become the focus. In order to protect the environment, the world refrigerator manufacturers are considering alternatie refrigerants CFCs. With non adiabatic capillary for research object:capillary, was born in the 1930s, and obtain patent in 1942. It is a through drawing process made hollow copper, inner diameter is usually 0.5～3mm, length to run the system is different in roughly 400～6000mm between. In order to let capillary of refrigerant maintain certain subcooling, usually with back tracheal parallel form back to hot capillary, namely said non adiabatic capillary. There are two kinds of composition way:and welding type and embedded type.Based on the above reasons, we needs to establish a reflect capillary thermodynamics and the flow characteristics in various mathematical models. Although the structure is simple, but the propellant in one of the flow and heat transfer phenomenon is very complicated. Especially for the unique thermal capillary, has yet to the flow inside the canal has a thorough research, theoretical calculation formula is relatively scarce. Actually, most or by experiment to determine the length, matching or flow, workload is considerable. This paper also can do a simple calculation, hope the inside of the thought for later research can make a reference, plays a role and textbooks. This paper firstly based on homogeneous flows to establish and perfect the mathematical model, and the simulation program, the division compiling process sequence simulation results analysis section of heat transfer condition of the working characteristic. And influence the performance of some parameters.The simulation results show that the non adiabatic capillary job characteristics and the adiabatic capillary are very different, this is obvious. When the heat exchange period began in super-cooling segment, the refrigerant in heat exchange segment will continue to cooling, subcooling into a step of increasing the length of the export section makes capillary also increases. If heat period began in two-phase segment, at this moment, capillary and inspiratory tube heat quite strongly, can make the part of refrigerant neatly to condensing become too cold liquid.