SINOPSIS

A usable concept for an ammonia evaporator in an absorption refrigerator based on a triple tube design is considered. The differential equations that describe the energy transfer between the ammonia refrigerant and the ammonia hydrogen gas mixture are utilized to simulate the thermal and hydrodynamic performances and hence to determine the operation of evaporator. This simulation procedure is used to determine the geometrical parameters of the evaporator, subject to certain optimization criteria that were incorporated in a cost function. The final design of the evaporator, which is based on 100 W of cooling power at −6.7 °C, has a length of 1.523 m and triple tube diameters of 28.5, 22.2, and 15.8 mm. The evaporator's design is such that only a single penetration through the refrigerator's wall is necessary, which greatly simplifies the construction and reduces its cost.