Modelling, Simulation and control of a Shortest Path Enthalpy Change Air Handling Unit with Liquid Desiccant

Abstract: In an abundance of industries, production lines and facilities, a correct indoor climate is an integral part to ensure the quality of the products and also very important for its occupants. To ensure a high quality air climate it is not enough to control the air temperature, air humidity is of at least equal importance. Most heating, ventilation and air conditioning systems (HVAC), are based on multiple treatment steps that each change both temperature and humidity. Due to the correlation between the temperature and relative humidity this results in system control difficulties, and unnecessary realignments to achieve the desired outputs. The novel Shortest path enthalpy change system (SPEC), developed by AirWaterGreen (AWG) with Controlled vapor pressure technology (CVP), aims to eliminate these problems. This is done by utilizing a method that may achieve the desired air quality with only one conditioning step, transferring heat and humidity simultaneously to or from the air. To validate this technology the work of this thesis is focused on producing a viable simulator model with verification, performed by comparing to a prototype system with the same technology. By verifying the simulator, it is also possible to continue development of the system by implementing system controllers within the Simulink environment. This provides the opportunity to ultimately obtain a highly efficient HVAC system with accurate setpoint control. In addition, the possibility of optimizing system dimensions is also investigated to allow for specific case configurations. The results show that high simulator accuracy is achievable, leading to a high confidence in the results, and showing that a PID or even proportional feedback controller is able to realize satisfactory system control. The optimization of dimensions shows that parallel computing is a fast way to reduce the amount of possible configurations that satisfy specific criteria. To support further development of the control and optimization of the system and ultimately hardware implementation, this thesis suggests points of interest for future work. These points include the improvement of ancillary simulator systems and further development of the pads physical equations, to increase the accuracy of process simulations, and the continued development of more complex controllers as well as their hardware implementation. Lastly, while focus of this thesis has been on the development of a functioning and controllable system, an important addition would be a study on the energy usage of the system and identifying points of interest for decreasing the total energy used from the system.