2016 ASHRAE Annual Conference

Commercial and industrial refrigeration systems consume a significant portion of US electrical energy. In this paper, advanced expansion valve and control algorithms are evaluated to quantify the potential energy savings due to improved system regulation and efficient start-up of vapor compression refrigeration systems. The performance of the new MEMS actuators with different control strategies is compared with the standard mechanical valves and a commercially available superheat controller. Additionally, this research includes a comprehensive set of experimental tests that identify the most effective elements of advanced valve control strategies, including the impact of refrigerant migration control strategies. The experimental results confirm that 30-50% improvements in cyclic COP are possible using improved expansion valve controls, while the benefits of preventing refrigerant migration do not outweigh the additional cooling achieved if refrigerant continues to flow through the expansion valve during the compressor off period.

Building operations account for approximately 40% of US energy use and carbon emissions, and vapor compression cycles are the primary method by which refrigeration and air-conditioning systems operate. Representing a significant portion of commercial and residential building energy consumption, vapor compression cycles are a target for improvement in efficiency and savings. This paper presents a data-driven approach to find the optimal operating conditions of single and multi-evaporator systems in order to minimize energy consumption while meeting operational requirements such as constant cooling or constant evaporator outlet temperatures. The control problem lies in the development of a control architecture that will minimize the energy consumed without requiring any models of the system or expensive mass flow sensors. The application of the presented approach improves efficiency, and is demonstrated in simulation and on an experimental system.

Centrifugal chillers are a significant investment in a centrally air-conditioned building system. Commercial centrifugal chillers are expensive so their maintenance should be the up-most priority for the buyer. It’s a great responsibility on the part of the buyer to maintain such an expensive machinery to maintain the economy of the company. The procedures presented in this paper apply to standard WSC/WDC/WCC family of chillers and HSC heat recovery chillers.