The effect of void fraction model on estimation of air conditioner system performance variables under a range of refrigerant charging conditions
Abstract One variable required for modelling the heat transfer and pressure drop of refrigerant inside air conditioner evaporators and condensers is the void fraction. Eight void fraction models were used in a refrigeration system model to evaluate their impact on the estimation of important system variables in an air conditioner as a function of charging. The void fraction models included: (i) homogeneous, (ii) Lockhart and Martinelli, (iii) Thom, (iv) Zivi, (v) Baroczy, (vi) Hughmark, (vii) Premoli and (viii) Tandon. The system variables considered included: power, capacity, refrigerant flow, subcooling and superheat. Comparisons were made with a 10.6 kW capacity air conditioner with capillary tube expansion. Results indicate that the Hughmark void fraction model appeared to provide the best comparison to measured data over the range of charging conditions considered.