Abstract: Unconditioned, sub-freezing turbine exhaust air is employed to cool liquid coolant from radar electronics in an aircraft. This is accomplished by utilizing a liquid/air exchanger. However, in order to ensure that the air-cooled heat exchangers do not experience freezing of moisture droplets, sufficient heat is supplied to a liquid/air heat exchanger, located at the turbine exhaust, to maintain all surfaces (fins) above freezing, and also to heat the entire turbine exhaust air stream to a temperature above freezing as it exits that heat exchanger. Use of this anti-icing liquid/air heat exchanger, in conjunction with the proper air and liquid flow controls, will permit savings of total cooling air (i.e., engine bleed air) flow by negating the need for a hot air bypass to reheat turbine exhaust air.

Abstract: In a normal mode, a primary heat exchanger for heated bleed airflow is situated upstream of an aircraft air conditioner compressor. A secondary heat exchanger is located downstream of the compressor. In response to hot and humid environmental conditions, three-way switching valves reposition the primary heat exchanger downstream of the compressor. The result will be the reduction of heat exchange exit temperature, which translates into lower turbine inlet and outlet temperatures at satisfactory airflow rates.