Experimental studies on a combined refrigeration/power generation system activated by low-grade heat

• This paper proposed a combined power/cooling system using low-grade waste heat.
• The experimental results were presented.
• The COP (coefficient of performance) of the refrigeration model is 0.448 when the cooling temperature is −9.07 °C.
• The heat-to-power conversion efficiency of the power generation model is 3.98%.

An experimental rig of a combined refrigeration/power generation system was built and investigated. This rig uses an ammonia–water binary working fluid, is driven by low-grade heat, and can function under the absorption refrigeration model and absorption power generation model. When the system was operated under the refrigeration model, the temperatures of the ethylene glycol solution that entered and exited the evaporator were −5.28 °C and −9.07 °C, respectively. The cooling output was 11.67 kW, and the corresponding coefficient of performance was 0.465. When the system was operated under the power generation model, the temperature and pressure of the turbine inlet were 94.66 °C and 8.55 bar, respectively. The turbine outlet pressure was 1.79 bar, the net power output was 1.02 kW (after 1 kW of power consumed by the solution pump was reduced), and the corresponding heat-to-power conversion efficiency was 3.98%. The combined system can achieve cooling and power generation and switch smoothly and easily between refrigeration and power mode. This study provides a feasible and flexible way to produce different products using low-grade heat.