Heat engines transfer high-temperature heat into mechanical and electrical energy using the Clausius Rankine Cycle (CRC). Low temperature applications primarily use the Organic Rankine Cycle, in which mainly waste heat, geothermal heat and solar heat are transferred into mechanical energy. The exergy of a low temperature heat source can be transferred into electricity in so-called triangle (or trilateral) cycles. By applying batch processes in heat engines, it is possible to reach an exceptionally high approximation to triangle cycles and thus to build up high exergy-efficient heat engines. In an example case the calculated exergy efficiency is 71% higher compared to a CRC. The proposed process is not limited to specific working media and can therefore be adapted to a wide range of temperatures. The required setup is rather simple and is derived from setups ranging from basic to more and more advanced. The thermodynamic performance of an example plant is derived from T-s-diagrams. (C) 2017 Elsevier Ltd. All rights reserved.