A novel combined throttle opening and variable valve timing strategy for combined cooling, heating, and power system flexibility

Abstract

The flexibility of combined cooling, heating, and power systems limits renewable energy penetration, supply–demand matching, and primary energy saving. The combined throttle opening and variable valve timing strategy adjust air flow, fuel consumption, and combustion duration, benefiting the operation range. The 1-D engine coupled with SIturb combustion model and quasi-steady absorption refrigerator were constructed. Traditional throttle opening and combined strategy are compared under a wide load range. The results indicate that exhaust energy was inversely correlated with brake thermal efficiency. The variable valve timing strategy regulated the exhaust energy to approach cooling load when power matched. The system operation range extended from a line to an area. At 100%, 70%, and 40% load, the adjustable cooling capacity was extended by 2.5%, 6.9%, and 28.9%, respectively. This suggests that the combined strategy improves the supply–demand matching, primary energy saving rate, and carbon dioxide emission reduction compared to the traditional throttle opening strategy.