 For other less efficient cycles, 〈"TH"〉 will be lower than "TH", and 〈"TC"〉 will be higher than "TC".This can help illustrate, for example, why a reheater or a regenerator can improve the thermal efficiency of steam power plants—and why the thermal efficiency of combined-cycle power plants (which incorporate gas turbines operating at even higher temperatures) exceeds that of conventional steam plants.The first prototype of the diesel engine was based on the Carnot cycle.