Numerical study of heat and mass transfer characteristics on a falling film horizontal tubular absorber for R-134a-DMAC

The present study investigates the flow, heat and mass transfer behavior of a falling film horizontal absorber by employing a two-dimensional numerical technique. The refrigerant, R-134a (1,1,1,2-tetrafluroethane) is absorbed by the falling film of the R-134a-DMAC (dimethyl-acetamide) solution. The related governing equations are solved using a developed computer code in MATLAB. The velocity, temperature and concentration fields in the domain are computed for varying operating parameters. The peak value of mass flux is found to decrease with increase in the solution flow rate and for higher solution flow rates the peak occurs at further downstream location on the tube surface. The local heat transfer coefficient is higher for lower solution flow rate and vice-versa. The mass transfer coefficient increases up to certain angular position and then begins to decrease. Optimum solution flow rate for maximum total mass flux corresponds to a particular tube diameter.