SEARCH · Engineering Papers

Results for “refrigerators”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22

All sources NASA NTRS DOE OSTI

NASA NTRS1975

Experimental and analytical investigation of 0 G condensation in a mechanical refrigeration system application

Basic equations of momentum and energy are presented and discussed with respect to heat transfer and pressure drop for forced flow condensation in horizontal tubes under 1-g and 0-g conditions. Some experimental results are presented for condensing refrigerant-12 in a system of three parallel-connected quartz tubes (3-mm inside diameter, G = 1.037 to 3.456 x 105 lbm/hr-sq. ft). From high speed photographs, measurements were obtained of film thickness, phase velocities, disturbance wavelengths, and flow regimes and their transitions. Based upon these measurements various dimensionless force ratios (flow and instability parameters) were calculated. Under 0-g conditions a uniformly thick redistribution of liquid condensate about the tube walls was found to result in a lowered heat transfer coefficient as compared with 1-g conditions, based upon fundamental heat transfer theory. A model is proposed that takes into account the difference in heat transfer due to condensate distribution under 1-g and 0-g conditions.

Keshock, E. G.↗

NASA NTRS1975

The performance of components in the Skylab refrigeration system

The on-orbit performance of the Skylab refrigeration system components is presented. Flight anomalies are analyzed and performance of the newly developed components is described. Nine months of orbit data proved the practicality of the leak-free coolant system design. Flight proven application of a thermal capacitor and development test results of the first all-mechanical, low temperature mixing valve represent a significant advance in single-phase, low temperature coolant loop design. System flight data suggest that additional instrumentation and fluid filters could have prevented system orbit performance anomalies.

Daniher, C. E., Jr.↗

NASA NTRS1978

Measuring cryogenic-refrigerator cooling capacity

Temperature-sensing bridge determines liquid reserve level in low-temperature heat exchanger. Device should be of interest to manufacturers of cryogenic refrigerators as well as to those who use them in conjunction with operation of electronic equipment like masers or Josephson junctions.

Wiebe, E. R.↗

NASA NTRS1977

A shock isolator for diode laser operation on a closed-cycle refrigerator

A device developed to isolate the diode laser from impact shocks delivered during the expansion phase of the Solvay cycle of a helium refrigerator is briefly described. The device uses intermediate cold stations in the stand-off, which permit the stand-off to be short and rigid while minimizing the thermal load at the diode mount.

Jennings, D. F.↗

NASA NTRS1978

Thermal compensator for helium refrigerators

Closed-cycle helium refrigerator sensor generates negative-feedback control signals that drive heating diode to maintain temperature stability. Temperature-sensing diode and heating diode are mounted on heat sink that provides conductive path between load and cold tip. Method is applicable to other temperature-control applications, such as laser equipment, electronic instruments, and computer systems.

Hillman, J. J.↗

NASA NTRS1978

Multistation refrigeration system

A closed cycle refrigeration (CCR) system is disclosed for providing cooling at different parts of a maser. The CCR includes a first station for cooling the maser's parts, except the amplifier portion, to 4.5 K. The CCR further includes means with a 3.0 K station for cooling the maser's amplifier to 3.0 K and, thereby, increases the maser's gain and/or bandwith by a significant factor. The means which provide the 3.0 K cooling include a pressure regulator, heat exchangers, an expansion valve, and a vacuum pump, which coact to cause helium, provided from a compressor, to liquefy and thereafter expand so as to vaporize. The heat of vaporization for the helium is provided by the maser amplifier, which is thereby cooled to 3.0 K.

Wiebe, E. R.↗

NASA NTRS1977

Active thermal compensator for diode laser stabilization on closed-cycle refrigerators

Cycling of a closed-cycle refrigerator produces temperature oscillations at the cold-tip which may be 0.5 K peak-to-peak. An active diode heater is described which compensates for the varying temperature and reduces the oscillations at the sample to about 0.003 K peak-to-peak at 9.5 K.

Jennings, D. E.↗

NASA NTRS1979

Solar-powered jet refrigerator

Design criteria are easily evaluated by tool. Thermodynamic analysis of solar-powered vapor-jet refrigerator combines important performance parameters in nomogram that assist design of practical system. Projected coefficients of performance for difference ejector configurations, working fluids, and other design variables are easily obtained from nomogram.

Chai, V. W.↗

NASA NTRS1978

Design theory and performance of cryogenic molecular adsorption refrigeration systems

Closed-cycle operation of molecular adsorption refrigeration systems (MARS) has been demonstrated by using thermally cycled zeolites to adsorb and desorb various gases under pressures of 20-60 atm. This paper develops three aspects of the design theory: the physical theory of molecular adsorption of small molecules such as A, N2, N2O and NH3, the design relations for closed-cycle flow for three or more compressors, and the coefficient of performance. This work is intended to demonstrate nonmechanical gas compression for various cryogenic gases than can compete with mechanical systems with a different mix of advantages and disadvantages.

Hartwig, W. H.↗

NASA NTRS1980

Progress on the development of a 3- to 5-year lifetime Stirling cycle refrigerator for space

A new approach to the development of a 3- to 5-year lifetime Stirling cycle refrigerator for space is described. The reciprocating components would be driven directly by linear motors. There would be no contact between the moving components and the machine housing or motor during operation. The noncontact operation can be achieved either by magnetic or gas bearings and clearance seals. Consequently, two major contractual efforts are underway, one to develop the magnetic-bearing cooler and the other to develop the gas-bearing machine. The coolers are required to have a 5-W capability at 65 K and to be dynamically balanced. The results of the major contractor phase 1 design definition studies and component testing are discussed. Both the gas-bearing and magnetic-bearing coolers show promise for achieving the 3- to 5-year lifetime goal.

Sherman, A.↗

NASA NTRS1981

Traveling-wave maser, closed cycle refrigerator automation

At the present time all traveling-wave maser and closed-cycle refrigerator system (TWM-CCR) and their power supply and helium compressor assemblies are operated manually. Many man-hours are required of highly trained and experienced operators, resulting in high operator cost. Of greater importance are the problems of unpredictable failure and long downtimes. Since field performance is not monitored, system degradation is detected only when it has progressed to the point of catastrophic failure. Without the aid of performance histories, failure diagnosis is arduous and slow. Rational and functional requirements for the TWM-CCR Automation project are the following: (1) to improve reliability and reduce downtime by providing unattended monitor and control, alarm and fault location, failure prediction and self-corrective action; (2) to reduce operator cost by providing automatic tuning and cooldown procedures; and (3) to improve system operations and development by providing the needed engineering data.

Mcneil, J. A.↗

NASA NTRS1984

Passive Module for Cryogenic Refrigeration

Refrigeration module with no moving parts attaches to cold plate of cryostat to reduce temperature. Module includes evaporation chamber, condenser and absorption pump.

Brooks, W.↗

NASA NTRS1982

Design of a horizonal liquid helium cryostat for refrigerating a flying superconducting magnet in a wind tunnel

The design of a horizontal liquid helium cryostat for refrigerating a flying superconducting magnet in a wind tunnel is presented. The basic principles of magnetic suspension theory are described and theoretical calculations of the superconducting magnet are provided. The experimental results of the boil-off of liquid nitrogen and liquid helium in the cryostat are reported.

Wu, Y. Y.↗

NASA NTRS1983

A refrigerated dynamic seal

A new sealing concept is proposed where the fluid to be sealed flows through a refrigerated housing or constriction, is frozen to the housing during the transient phase, and under steady state conditions provides a dynamic seal with essentially 'zero' leakage.

Hendricks, R. C.↗

NASA NTRS1983

Cycling Joule Thomson refrigerator

A symmetrical adsorption pump/compressor system having a pair of mirror image legs and a Joule Thomson expander, or valve, interposed between the legs thereof for providing a, efficient refrigeration cycle is described. The system further includes a plurality of gas operational heat switches adapted selectively to transfer heat from a thermal load and to transfer or discharge heat through a heat projector, such as a radiator or the like. The heat switches comprise heat pressurizable chambers adapted for alternate pressurization in response to adsorption and desorption of a pressurizing gas confined therein.

Tward, E.↗

NASA NTRS1983

An application of gap regenerator/expander precooled by two stage G-M refrigerator

The degradation of regenerator effectiveness below 10K is due to the imbalance of the heat capacity of the regenerator material and helium gas as a working fluid. One of the attractive methods to increase this efficiency could be realized by a gap regenerator system regarding helium gas property. This paper describes an experiment using pressurized helium gas as a regenerator material. A two stage G-M cycle refrigerator has been used for precooling the gap regenerator system. With this method, minimum temperature below 5K has been obtained when the precooling temperature maintained at 10K.

Matsubara, Y.↗

NASA NTRS1984

Design considerations for a HE-3 refrigerator for space applications

The low temperature provided by He-3 refrigerators (0.3 to 3 K) have useful space applications. However, the low temperatures and the low surface tension of He-3 require special design considerations. The considerations include the need for small pores to contain the liquid in a matrix; the effects of bubble nucleation and growth; and the effects of the thermal conductivity within the matrix. These design considerations are discussed and a possible confinement system is analyzed.

Kittel, P.↗

NASA NTRS1982

Design, installation and operating experience of 20 photovoltaic medical refrigerator systems on four continents

The NASA Lewis Research Center in cooperation with the World Health Organization, U.S.A. I.D., the Pan American Health Organization and national government agencies in some developing countries sponsored the installation of twenty photovoltaic powered medical vaccine storage refrigerator-freezer (R/F) systems. The Solar Power Corporation was selected as the contractor to perform the design, development and installation of these twenty units. Solar Power's experiences are described herein.

Hein, G. F.↗