Gas engines are widely applied as basic engines in integrated energy systems (IES) for combined power, heat and refrigeration. However, the highest thermal efficiency is achieved at full matching heat released from engine and heat transformed. This is practically impossible in actual practice, especially if the heat is transformed into refrigeration by the most efficient and widespread absorption lithium-bromide chillers (ACh), so as their heat consumption is limited by feeding hot water temperature drop by approximately 15 ℃. Therefore, the heat not consumed by ACh is rejected through emergency radiator to the atmosphere. The unused heat might be transformed by ejector chiller (ECh) as the simplest and cheapest but comparably low efficient with COP from 0.2 to 0.35 against 0.7 to 0.8 for ACh. Therefore a rational distribution of the heat released from engine between ECh and ACh has been conducted to enhance COP of ECh. The corresponding method was developed taking into account a dependence of ECh cooling capacity and COP from the temperature potential of the heat released from engine. The new system ensuring efficient conversion of exhaust heat for cooling engine intake air and enhancement of fuel efficiency was developed. It provides reduction of specific fuel consumption by 1.5 to about 3.0 g/kWh. The schemes of heat transforming system based on cooperative functioning ACh and ECh was developed proceeding from distribution of the available heat. So as a thermodynamic efficiency of combustion engine is influenced essentially by intake air temperature, the refrigeration of ECh is expediently used for sucked air conditioning to ensure sustainable operation of the engine at lowered intake air temperature with high fuel efficiency.