Regulation of flow using P, PI and PID controllers inside a temperature controlled cold room

Transient, laminar and incompressible air flow inside a vented cavity representing a realistic cold room model has been investigated numerically in the presence of three temperature dependent continuous (P, PI and PID) controllers. This model contains a variable air flow cooler, an exit ventilation, a closed entrance door and an isoflux heat source. The inflow of cold air is regulated by a controller, which always tries to keep the controlled variable (temperature of the room) to a set point temperature. The governing mass, momentum and thermal energy equations in transient state are solved using Galerkin finite element method in order to evaluate flow and thermal fields inside the vented cavity. Values of proportional gain, integral gain and derivative gain are varied to obtain the desired system response and to ensure a stable system with fastest response and better accuracy. At first, the performance of only P controller is analyzed and then, the usage of PI and PID controllers is investigated based on the reference (set point) temperature which is continuously monitored at a certain location (point of interest) inside the cold room. It is found that PID controller has fastest response, better accuracy and stable performance.