A new capacity controller for a direct expansion air conditioning system for operational safety and efficiency

For achieving a balance between the operational safety and efficiency of a variable speed direct expansion air conditioning system, a new capacity controller that can not only simultaneously control indoor air temperature and humidity, but also select an optimized degree of superheat setting to properly balance the operational safety and efficiency has been developed, by adding a control module to a previously developed capacity controller. The core of the control module was an artificial neural network based model representing the known relationship between the inherent operational characteristics and operational stability of a variable speed direct expansion air conditioning system. Using the control module developed, the degree of superheat setting could be varied in accordance with the variation in operating conditions for ensuring a safe and an efficient operation. The performance of the new capacity controller was experimentally tested using an experimental variable speed direct expansion air conditioning system. Controllability test results showed that the system hunting was mitigated when a larger degree of superheat setting was selected by the developed control module and an improvement in COP at about 3.4% was achieved when a smaller one was selected when using the new capacity controller for simultaneously controlling indoor air temperature and humidity. Practical application: This paper reports a new capacity for a VS DX A/C system, which can not only control indoor air temperature and humidity through varying compressor and supply fan speeds, but also select an optimized DS setting for ensuring both a safe and efficient system operation. The controllability test results showed that the new capacity controller could be applied to DX A/C systems for indoor thermal control with a higher operational safety and energy efficiency.