Design and construction of a pumped refrigerant loop for commercial scale low-GWP refrigerant heat exchanger testing

Abstract

A pumped refrigerant loop for refrigerant conditioning is developed to allow testing of heat exchangers using a wide range of refrigerants, including low global warming potential refrigerants. The pumped refrigerant loop can be connected to the tested heat exchanger within the OSU Psychometric Coil Testing Facility. The pumped refrigerant loop provides refrigerant for a range of temperatures including for comfort cooling conditions at around 12 degrees C and high temperature refrigeration applications at about 1 degrees C. Depending on refrigerant temperature and quality, the maximum cooling capacity for the tested heat exchanger varies from 4 to 12 tons. The pumped refrigerant loop allows fine control of the flowrate within an anticipated 1% of flow and 1.5% of inlet quality to the tested heat exchanger. A secondary pumped glycol loop uses 40 kW of electric heat to control the refrigerant subcooling and quality - or alternatively can be sued as an 11+_ton heat source if the tested coil is a condenser. This secondary loop can additionally be used for hydronic coil testing in the Coil Testing Facility. This thesis presents the development of a steady state model for the pumped refrigerant loop. That model is then used with specific design conditions for sizing and selection of components. This thesis additionally presents the development of other subsystems including data acquisition, control system, and safety circuit. An appendix provides numerous annotated pictures of the construction of the setup.