An environmental control system includes an inlet configured to receive a medium and a compressing device fluidly connected to the inlet. The compressing device includes a compressor operably coupled to a turbine. An outlet of the compressor is fluidly connected to an inlet of the turbine such that the medium is provided to the compressor and the turbine in series. At least one air-liquid heat exchanger is arranged in fluid communication with the outlet of the compressor and the inlet of the turbine. The at least one air-liquid heat exchanger is also connected to a liquid loop containing a liquid. At least one air-liquid regeneration heat exchanger is fluidly connected to the liquid loop at a location upstream from the at least one air-liquid heat exchanger.