Frost; Evaporator; Refrigeration; Optimization; Energy consumption
This work is aimed at the optimal design (i.e. number of transversal and longitudinal tube rows, number of fins) of fan-supplied tube-fin evaporators for light commercial refrigeration applications operating under frosting conditions. Quasi-steady-state algebraic models were put forward for the refrigeration cycle and its components for computing not only the cooling capacity depletion due to the evaporator frosting over time, but also the changes experienced by the evaporating temperature and its effect on the compressor power. Transient, unsteady-state algebraic models were also advanced to account for the temperature and humidity variations inside the refrigerated compartment, and so the compressor runtime. The optimization exercise aiming at system-level energy consumption minimization revealed that, when the evaporator volume and width are held constrained, the lowest energy consumption was achieved for evaporators with evaporators with (3x6), (4x4) and (6x3) (transversal ´ longitudinal tubes), suggesting that the geometry is robust regarding the evaporator aspect ratio for fan-constrained conditions.