Controlling LPG temperature for SI engine applications

In this study, the effects of the LPG temperature on the engine performance and the exhaust emission characteristics have been investigated experimentally on an SI engine. In conventional injection systems, the LPG temperature increases excessively during the phase change in pressure regulator, and reduces the engine volumetric efficiency. According to the test results, engine performance and NO emission characteristics can be improved by controlling the LPG temperature before injecting to the engine intake manifold. A new control system taking into account the results of the study has been developed and tested. In order to control the LPG temperature, the coolant flow rate in pressure regulator circuit was arranged by using a control valve activated by a PID controller unit. Results of the study showed that the engine brake power loss can be increased by about 1.85% and NO emissions can be decreased by about 2% as compared to the operation with the original LPG injection system. (C) 2015 Elsevier Ltd. All rights reserved.