Cylinder steam injection (CSI) for internal combustion (IC) engine waste heat recovery (WHR) and its application on natural gas (NG) engine

On Direct Injection of Supercritical Water into Spark Ignition Engines as a Strategy for Heat Recovery

“…The use of direct water injection as an energy recovery approach is a very recent strategy and is being studied by various researchers. [ 13–16 ] In the studies by Zhang and Li [ 13 ] and Li and Zhang, [ 14 ] GT‐POWER solver was used to estimate the potential efficiency benefit of in‐cylinder direct injection of the steam superheated by the thermal energy of exhaust gas. The steam was injected into the engine chamber during the compression stroke of a turbocharged diesel engine, [ 13 ] whereas in Li and Zhang [ 14 ] during the expansion stroke of a natural gas turbocharged engine, with an appropriate timing to avoid an interaction with combustion.…”

“…In other words, injection starts at the end of combustion, in order for the supercritical water not to interfere with the flame itself. A similar approach has been found in a very recent work, [ 16 ] where a preheater was used to increase the water temperature up to K by recovering heat from the coolant and the injection pressure was set to bar. In this work, an injection pressure equal to bar is considered and water temperature is increased up to K in the preheater.…”

“…In addition, a different numerical approach is used to compute the temperature of the exhaust gas leaving the combustion chamber. In the study by Liu et al, [ 16 ] the water vapor temperature was computed based on the exhaust gas temperature, which was measured in the engine in the absence of water injection. In this work, the water injection temperature is computed based on the temperature of the exhaust gas, which flows through the heat exchanger, and is also influenced by the injection conditions and the amount of water injected.…”