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Kirkpatrick, J. P.

Publications and source records attributed to Kirkpatrick, J. P..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Entrainment, Drizzle, and Cloud Albedo

Increased aerosol and hence droplet concentrations in polluted clouds are expected to inhibit precipitation and thereby increase cloud water, leading to more reflective clouds that partially offset global warming. Yet polluted clouds are not generally observed to hold more water. Much of the uncertainty regarding the indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations show that the relative humidity of air overlying stratocumulus is a leading factor determining whether cloud water increases or decreases when precipitation is suppressed. When the overlying air is dry, cloud water can decrease as droplet concentrations increase.

Ackerman, A. S.↗
NASA NTRS1976

"Thermal-diode" heat pipe

Device transfers heat in one direction and blocks heat transfer in opposite direction.

Kirkpatrick, J. P.↗
NASA NTRS1976

Heat pipes for spacecraft temperature control: An assessment of the state-of-the-art

Various heat pipe temperature control techniques are critically evaluated using characteristic features and properties, including heat transport capability, volume and mass requirements, complexity and ease of fabrication, reliability, and control characteristics. Advantages and disadvantages of specific approaches are derived and discussed. Using four development levels, the state of-the-art of the various heat pipe temperature control techniques is assessed. The need for further research and development is discussed and suggested future efforts are projected.

Kirkpatrick, J. P.↗
NASA NTRS1976

Heat pipes for spacecraft temperature control: An assessment of the state-of-the-art

Spacecraft applications that require the efficient cooling of high-powered components, the precise temperature control of sensitive electronic and optical components, and the protection of cooled components from temporary, adverse environmental conditions are increasing. Heat pipes using gas, vapor, liquid, or voltage control to provide variable conductance or diode thermal behavior have been and are continuing to be developed to meet increasingly difficult requirements. The various control techniques are critically evaluated using characteristic features and properties, including heat transport capability, volume and mass requirements, complexity and ease of fabrication, reliability, and control characteristics. As a result, advantages and disadvantages of specific approaches are derived and discussed. Using four development levels, the state-of-the-art of the various heat pipe temperature control techniques is assessed.

Groll, M.↗
NASA NTRS1976

Long term performance of the advanced thermal control flight experiment

The Advanced Thermal Control Flight Experiment (ATFE) is providing the first zero-g flight data for the performance of a thermal diode heat pipe and an electrical Feedback Controlled Heat Pipe (FCHP). The temperature stability derived from the melting and freezing of octadecane is also being evaluated in this experiment. Flight data for the different operational modes are compared to ground test data, and the performance of the individual components is analyzed. Also, the ATFE's long term behavior from launch through September 30, 1975, is evaluated. The temperature control capability of a thermal diode, phase change material, and FCHP was demonstrated over more than 500 days of flight operation and each of these components should be considered in future applications. Both the diode and FCHP transport more than 20 W in the normal and passive modes during maximum conditions. Up to 30 W has been carried by the FCHP when the auxiliary heater is applied. The "OFF-conductance" of the diode has improved substantially in flight. A 1.4 W decrease in backflow has been realized by more complete blockage. The variable conductance behavior of the FCHP is essentially unchanged with time and relative to ground tests. Degradation of the radiator and reservoir surfaces have resulted in a partial loss of control by the FCHP during normal mode operation; however, manual control at an elevated set point has demonstrated the FCHP's ability to provide regulated temperature control to within + or - 2 C. The same pipe when operated as a passive VCHP controlled at 35 + or - 10 C with the same test conditions.

Brennan, P. J.↗
NASA NTRS1975

ATS-6 - Flight performance of the Advanced Thermal Control Flight Experiment

The Advanced Thermal Control Flight Experiment on ATS-6 was designed to demonstrate the thermal control capability of a thermal diode (one-way) heat pipe, a phase-change material for thermal storage, and a feedback-controlled heat pipe. Flight data for the different operational modes are compared to ground test data, and the performance of the components is evaluated on an individual basis and as an integrated temperature-control system.

Kirkpatrick, J. P.↗
NASA NTRS1975

A variable conductance heat pipe flight experiment - Performance in space

The Ames Heat Pipe Experiment (AHPE) is a variable conductance heat pipe/radiator system which was launched aboard the OAO-C spacecraft in August, 1972. All available flight data was reviewed and those from a few orbits were selected for correlation with predictions from an analytical model of the system. The principal conclusion of this study is that gas controlled variable conductance heat pipes can perform reliably for long time periods in the space environment and can effectively provide temperature stabilization for spacecraft electronics. Furthermore, the performance of such systems can be adequately predicted using existing analysis tools.

Wanous, D. J.↗
NASA NTRS1975

Performance analysis of the advanced thermal control flight experiment

Flight data for the different operational modes of the advanced thermal control flight experiment are presented and compared with ground-test data. Performance of the system with feedback control is compared to performance without such control, and performances of the individual components are analyzed. Finally, changes in performance from launch through March 31, 1975, are discussed and analyzed. All thermal control components are performing as predicted for the existing flight environment. However, the daily reservoir and radiator temperatures during peak solar input are greater than those experienced in ground acceptance tests. These increased temperatures have resulted in a loss of control by the feedback-controlled variable-conductance heat pipe for several hours around the period of maximum insolation. The higher temperatures are apparently due to contamination and/or degradation of the second-surface mirrors which cover the reservoir and radiator.

Kirkpatrick, J. P.↗
NASA NTRS1974

Parametric performance of extruded axial grooved heat pipes from 100 to 300 K

Extensive performance data derived from tests with an aluminum axial grooved extruded heat pipe is presented for oxygen, methane, ethane, and ammonia as working fluids. The effects of operating temperature, fluid inventory, heat flux, and elevation on the transport capability and the evaporator and condenser film coefficients are measured and compared to theory. The data correlation indicates that, in addition to the viscous pressure drop of the fluid, a vapor induced liquid pressure drop must be taken into account at temperatures near or below the normal boiling point of the fluid. Methane, ethane, and ammonia are all suitable working fluids for this groove geometry; however, oxygen, because of its low static height, is at best marginal in the 100-120 K range.

Schlitt, K. R.↗
NASA NTRS1973

Variable conductance heat pipes from the laboratory to space

Heat pipes were developed which can be used as (1) a variable conductance link between a heat source and sink which provides temperature stability; (2) a feedback control mechanism that acts to directly maintain the source at a constant temperature; (3) or as a thermal diode that allows heat to be transferred in one direction only. To establish flight level confidence in these basic control techniques, the Ames Heat Pipe Experiment (AHPE) was launched in August 1972 and the Advanced Thermal Control Flight Experiment (ATFE) is scheduled for launch in May 1973. The major efforts of the technology development, initial flight results of the AHPE, and ground test data of the ATFE are discussed.

Kirkpatrick, J. P.↗
NASA NTRS1973

Advanced Thermal Control Flight Experiment.

The advanced Thermal Control Flight Experiment on the Applications Technology Satellite (ATS-F) will evaluate, for the first time in a space environment, the performance of a feedback-controlled variable conductance heat pipe and a heat pipe thermal diode. In addition, the temperature control aspects of a phase-change material (PCM) will be demonstrated. The methanol/stainless steel feedback-controlled heat pipe uses helium control gas that is stored in a wicked reservoir. This reservoir is electrically heated through a solid state controller that senses the temperature of the heat source directly. The ammonia/stainless steel diode heat pipe uses excess liquid to block heat transfer in the reverse direction. The PCM is octadecane. Design tradeoffs, fabrication problems, and performance during qualification and flight acceptance tests are discussed.

Kirkpatrick, J. P.↗
NASA NTRS1972

A variable conductance heat pipe/radiator for the lunar surface magnetometer.

The device was developed to supplement the existing cooling system of the Apollo 16 Lunar Surface Magnetometer (LSM). Analysis and tests showed that two such devices, inserted by an astronaut into receptacles on opposite sides of the electronics package, would reduce the diurnal temperature variation by about 40% and thereby would considerably increase the reliability of 50,000 welded connections. The LSM design constraints, selection of a variable conductance technique, heat pipe/radiator design features, and thermal performance are discussed.

Kirkpatrick, J. P.↗