Design of a PID controller to regulate the hot water temperature of a heat pump operating with CO2 and a solar evaporator
Carlos Eduardo Castilla Alvarez1; Hugo Sgarbi Campos1; Luiz Machado1; Antônio Augusto Torres Maia1; Ricardo Nicolau Nassar Koury2
1 Universidade Federal de Minas Gerais; 2 niversidade Federal de Minas Gerais
doi:10.20906/CPS/COB-2015-1692
Resumo
The interest in natural fluids as substitutes for the traditional CFCs and HCFCs has been rising. The CO2 has been considered as one of the most promising alternatives, especially in heat pumps for heating residential water. The systems that operate with this fluid generally present elevated efficiency reduced size. The utilization of CO2 combined with solar assisted evaporators is a strategy that is being used for improving COP of the heat pumps. But, due to events that are hard to predict like the water condensation and the insolation variation, the hot water temperature may present substantial variation. In this paper is presented the project of a PID (Proportional-Integral-Derivative) controller to regulate the outlet water temperature of a domestic heat pump. The controller tuning was performed employing methods described in the literature. The controller was subject to computational simulations to evaluate aspects like robustness, disturbance rejection, stabilization time and steady state error. Employing different performance rates, the best tuning method for the system presented in this study was the ITAE method.
Palavras-chave: heat pump; water temperature; control system