Vapor compression refrigeration testing on parabolic flights: Part 2 - heat exchanger performance

Brendel, Leon P. M.; Caskey, Stephen L.; Braun, James E.; Groll, Eckhard A.

doi:10.1016/j.ijrefrig.2021.12.013

Cited by 7 publications

(3 citation statements)

References 7 publications

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“… Bortolin et al 69 Collection of experimental results from ESA ENCOM project (parabolic flight) Axially symmetrical curvilinear fin with 15 mm height HFE-7100 Natural convection T sat = 51 °C Liquid film thickness measurements Flow visualizations Maximum local HTC detected at the tip of the fin and at the conjugation area of condensed film and the meniscus at the bottom of the fin. Brendel et al 23 , 24 Experimental (parabolic flights) Fin-and-tube condenser (6.2 mm ID, 16.8 m total coil length) in a vapor compression cycle R134a T sat = 25.6–31.6 °C G = 15.2–35.1 kg m −2 s −1 Flow visualizations Check of the stability of the system Condensation pressure rise by 3% under microgravity compared to normal gravity. Chen et al 4 Review of numerical, analytical and experimental works Flat surfaces, microgrooves, smooth and microfinned channels, round and rectangular minichannels Steam and refrigerants Assessment of the influence of gravity, shear stress, surface tension, and capillary and centrifugal forces on condensation heat transfer Large potential for the use of vapor shear to remove the condensate in space applications.…”

Section: Introductionmentioning

confidence: 99%

“…Analysis of pressure signals in terrestrial condensing systems reveals the presence of oscillatory phenomena due to transient flow which can be encountered also in microgravity and hypergravity conditions and may impact the thermal performance of the cooling devices 22 . The stability and the performance of a vapor compression cycle working with R134a under varying gravity accelerations were experimentally investigated by Brendel et al 23 , 24 during parabolic flight campaigns. The onset of microgravity was found to cause a steep increase of the condensation pressure up to 3% due to the reduced liquid removal from the walls and the decreased heat transfer coefficients compared to normal gravity.…”

Section: Introductionmentioning

confidence: 99%

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Condensation heat transfer in microgravity conditions

et al. 2023

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In the present paper, a thorough review of the experimental and numerical studies dealing with filmwise and dropwise condensation under microgravity is reported, covering mechanisms both inside tubes and on plain or enhanced surfaces. The gravity effect on the condensation heat transfer is examined considering the results of studies conducted both in terrestrial environment and in the absence of gravity. From the literature, it can be inferred that the influence of gravity on the condensation heat transfer inside tubes can be limited by increasing the mass flux of the operating fluid and, at equal mass flux, by decreasing the channel diameter. There are flow conditions at which gravity does exert a negligible effect during in-tube condensation: predictive tools for identifying such conditions and for the evaluation of the condensation heat transfer coefficient are also discussed. With regard to dropwise condensation, if liquid removal depends on gravity, this prevents its application in low gravity space systems. Alternatively, droplets can be removed by the high vapor velocity or by passive techniques based on the use of condensing surfaces with wettability gradients or micrometric/nanometric structuration: these represent an interesting solution for exploiting the benefits of dropwise condensation in terms of heat transfer enhancement and equipment compactness in microgravitational environments. The experimental investigation of the condensation heat transfer for long durations in steady-state zero-gravity conditions, such as inside the International Space Station, may compensate the substantial lack of repeatable experimental data and allow the development of reliable design tools for space applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Condensation heat transfer in microgravity conditions

et al. 2023

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“…The review identified examples of other cold storage technologies used in space, such as Stirling cycle, reversed Brayton cycle and thermoelectrics. Subsequently, in 2022, the same group published experimental results from their own VCC refrigeration tests during parabolic flights [13,14].…”

Section: Introductionmentioning

confidence: 99%

Assessing the Potential of Heat Pumps to Reduce the Radiator Size on Small Satellites

Bennett

Lim²

2023

Energies

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Future small satellites will demand high-performance on-board electronics, requiring sophisticated approaches to heat rejection beyond simply increasing the radiator surface area. An interesting alternative approach is to increase the surface temperature of the radiator, using a heat pump. In this study, calculations were carried out to compute the theoretical radiator size reduction potential enacted by having a heat pump as part of a satellite’s thermal management system. The practical likelihood of a ‘typical’ vapor compression cycle (VCC) heat pump satisfying theoretical requirements was considered. In agreement with theoretical calculations, employing a ‘typical’ VCC heat pump could either increase or decrease the required radiator surface area. The choice of heat pump and its design is therefore crucial. A heat pump with a large temperature lift is essential for satellite radiator cooling applications, with the coefficient of performance (COP) being less important. Even with a low COP, such as 2.4, a ‘typical’ heat pump providing a large temperature lift, close to 60 °C, could reduce the satellite’s radiator surface area by a factor close to 1.4. This is a significant potential reduction. The decision on whether to pursue this approach compared to alternatives, such as deployable radiators, should consider the relative complexity, cost, weight, size, reliability, etc., of the two options. The focus of this study is VCC heat pumps; however, the results provide performance targets for less mature heat pump technologies, e.g., caloric devices, which could ultimately be applied in space.

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