Exhaust Heat Utilization of a Household Generator Engine for Refrigeration Purposes: Case Study

The exhaust gas heat of an internal combustion engine (ICE) can potentially yield the cooling effect of a diffusion absorption refrigerator (DAR). One of the electricity generators in rural areas is a significant source of exhaust waste heat. The exhaust waste heat recuperation of the ICE of a domestic electricity generator was experimentally assessed to operate a DAR system. The experimental assembly consists of a set of household generator engines and a waste gas heat exchanger to operate the absorption test system, which utilizes an Electrolux refrigerator (RM212, F). The system was tested under various operating conditions, based on the engine loading ratios (i.e., 0%, 30%, 60%, and 90% of the total load of the test engine), as well as the operating condition of the electrical resistance (electric heater). The steady-state results of the exhaust gases' temperatures ranged between (400°C) and (500°C) at load conditions of 0% to 60%, which are suitable for running the DAR system. The evaporator surface temperatures decreased in all operating cases except for the case (90%), where a negative effect appeared owing to the high thermal energy in the engine exhaust gas. Accordingly, an optimised heat source was adopted, bypassing part of the exhaust stream under this loading condition (90% WI) to avoid overheating of the refrigerant fluid. Furthermore, the lowest surface temperature of the evaporator in the absorption system was recorded (−1.1 °C) at a load of (30%). On the other hand, the highest value of the system performance coefficient was (0.0953) under the load-high condition with an optimized heat source (90% WI). Based on the positive cooling effect of the N tested system, it can be adopted as supplementary equipment for refrigeration purposes in rural areas with energy-saving prospects.