Vapor compression refrigeration testing on parabolic flights: Part 1 - cycle stability. (April 2022)

• Record Type: Journal Article
• Authors: Brendel, Leon P.M.; Caskey, Stephen L.; Ewert, Michael K.; Lee, Frank Kwok; Braun, James E.; Groll, Eckhard A.
• Is Part Of: International journal of refrigeration. Volume 136(2022)
• Page Start: 152
• Page End: 161
• Publication Date: 2022-04
• Subjects: Refrigeration -- Vapor compression -- Microgravity -- Parabolic flights -- Orientation -- Gravity; Froid [artificiel] -- Compression de vapeur -- Microgravité -- Vols paraboliques; Refrigeration and refrigerating machinery -- Periodicals; 621.56
• DOI: 10.1016/j.ijrefrig.2022.01.023
• Languages: English
• ISSNs: 0140-7007

Abstract

Highlights: First vapor compression refrigeration cycle experiment on parabolic flights. Simple stability indicators show on average less than 15% changes for different measurements across range of operating conditions. Loss of superheat due to parabolas observed for initial condition of less than 3 Kelvin superheat at onset of parabola maneuvers. Comparison of operational changes due to parabolas with effects of varying inclination angle in a laboratory. Abstract: Long duration manned space travel is projected to bring a need for large cooling capacities in microgravity for typical freezing and refrigeration temperatures. Among possible cooling technology alternatives, the vapor compression cycle has the highest coefficient of performance but the confidence for microgravity applications is very low. This research effort experimentally investigated the effects of hyper and microgravity on a vapor compression cycle during parabolic flights. A total of 122 parabolas were flown over four days with a repeating pattern of 5 sequential parabolas. Transient data of the evaporation temperature and cooling capacity for selected parabolas are presented as the test stand experienced alternating hyper and microgravity levels. Most measurements and performance indicators showed mild effects on the cycle operation during the varying g-forces. For example, the refrigerant side cooling capacity fluctuated on average within a band of 15% (+/-7.5%) through all sets of parabolas. A loss of superheat due to gravity changes was observed for one set of parabolas but the set was started with an unusually low superheat of only 3 K. For all other sets of parabolas, superheat and subcooling were maintained. Flight results were compared with inclination testing in a laboratory using the same test stand. Inclination changes from -90° to + 90° impacted both the liquid and suction line mass flow rate while varying the gravity level between 0 and 1.8 g affected the suction line mass flow rate but not the liquid line mass flow rate.