Analysis of combined cooling,heating,and power systems operating following the electric load and following the thermal load strategies with no electricity export

Technologies such as cogeneration and trigeneration have great potential for energy and emission reduction because these technologies make better use of fuels by recovering waste heat to satisfy thermal loads. Operation of a system that involves several types of equipment operating as one unit, that at the same time interact with the building to meet its energy demand, requires an operational strategy that makes the system operate properly. This means the system must be able to respond to the building energy demand while having the best performance within the constraints imposed by the operational strategy. When a cogeneration system (combined heating and power) or trigeneration system (combined cooling, heating, and power) operates at partial load, the operational strategy has particular effect on the performance of the system. Two common operational strategies to operate these systems are following the electric load and following the thermal load. This article presents a methodology that allows selecting the right operational strategy based on the ratio between the building electric and thermal loads, and the ratio between electricity demand and size of the power generation unit when exporting electricity is not an option. Results show that the following the thermal load strategy seems to be better than the following the electric load strategy for most cases. Therefore, the methodology presented in this article is a decision-making tool for the selection of the right operational strategy.