Medium capacity low charge ammonia chiller and heat pump

Large-scale ammonia refrigeration and heating systems have been widely used in industry due to their high efficiency, broad temperature ranges of operation and innocuous environmental effects. However, implementation of this technology in small to medium systems has not yet been very successful. Factors like the toxicity of the refrigerant and prices of ammonia equipment are some of the obstacles that this technology must overcome before being able to enter a market dominated by systems running on HFC refrigerants. This paper presents a concise review of the research and development of ammonia systems designed to supply small to medium capacity applications. Based on this review, a low charge ammonia chiller and heat pump unit intended to supply both needs providing 180 kW of cooling and 200 kW of heating was proposed. A market overview was performed to find the available equipment that can guarantee proper operation with the lowest possible refrigerant charge. Furthermore, a numerical study of three concepts for this system was performed to study the performance, as well as refrigerant charge estimation and distribution within the equipment. The analysis laid the foundation to propose a suitable configuration to embrace the intended market segment not only considering the high coefficient of performance but also specific refrigerant charge.