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Development of a flexible thermosyphon for cooling a concentrated heat source

Description: A flexible tubular thermosyphon was developed for the purpose of cooling a concentrated heat source. Designed to fold 180{degrees} for storage and unfold for operation, the thermosyphon is made of copper and uses water as the working fluid. Its integral flex-joint has several advantages over conventional flexible joints. A unique boiling enhancement improved the liquid-to-vapor phase change while minimizing the conduction-temperature drop from the tube wall to the fluid, and was found to perform better than a screen wick in the evaporator. A study of the power limits and of other working fluids was conducted with the HTPIPE computer code (Los Alamos). Power limits were calculated to be far in excess of what was needed, but experiments revealed that the limits were significantly lower. Water was predicted to be the best working fluid at the operational temperature range but this was not experimentally verified.
Date: May 1, 1995
Creator: McKee, R.S. & Hobbs, F.D.
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Techniacl progress report, June 1, 1995--July 31, 1995

Description: The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Technical progress report, August 1, 1995--September 30, 1995

Description: The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Technical progress report, December 31, 1995--January 31, 1996

Description: The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Technical progress report, July 15, 1996--September 14, 1996

Description: This report very briefly summarizes project objectives, results, and current activities. The goals of the project are: (1) to develop guidelines for the design and use of thermosypohon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. Results include the experimental study of thermosyphon heat exchangers, which led to modeling equations that correlate the overall heat transfer coefficient-area product (UA) to mixed convection regime parameters. Current activities include the development and evaluation of a side-arm heat exchanger computer model and modification of the experimental facility for fundamental heat exchanger studies.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Technical progress report, May 15, 1996--July 14, 1996

Description: This progress report very briefly summarizes study results and includes an experimental plan developed for the fundamental study of heat transfer in thermosyphon side-arm heat exchangers. The study will investigate the influence of the Reynolds and Grashof numbers on the thermosyphon flow side of the heat exchanger, and the influence of the flow rate on the forced flow side of the heat exchanger. Detailed temperature, flow rate, and pressure data will be obtained for four, seven, and nine tube-in-shell heat exchanger designs. Correlations will be developed for the heat transfer and friction coefficients, and a semi-empirical model will be developed to predict the performance of thermosyphon heat exchangers in solar water heaters.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Technical progress report, September 15, 1996--November 14, 1996

Description: The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

Colorado State University Program for developing, testing, evaluating, and optimizing solar heating and cooling systems. Project status report, June 1994--July 1994

Description: This report describes integrated tank/heat exchanger modeling and experiments. Experiments were performed on a Rheem wrap-around 80 gallon electric hot water heater tank with the bottom heating element replaced by a 120 feet long coil of copper tubing wrapped around the outside lower half of the tank. The bottom two-thirds of the tank is heated by hot antifreeze circulating from the solar collector through the copper coil. Results are discussed.
Date: September 1, 1995
Partner: UNT Libraries Government Documents Department

Natural convection heat exchangers for solar water heating systems. Technical progress report, February 1, 1996--March 31, 1996

Description: This progress report describes the thermodynamic testing and modeling of a thermosyphon heat exchanger used in solar water heating systems. Testing of a four tube-in-shell thermosyphon heat exchanger was performed in two parts. The first portion of the test increased the collector fluid while the storage tank remained isothermal. After the collector fluid temperature was raised to 95 C, the second part of the test allowed the storage tank to gain heat. The test was performed for two collector flow rates. Measured values included collector side forced flow rate, temperature differences across the heat exchanger, vertical temperature distribution in the storage tank, vertical water temperature profile in the heat exchanger, and pressure drop on the thermosyphon side of the heat exchanger. The overall heat transfer coefficient-area product (UA) values obtained confirmed that models which assume UA depends solely on thermosyphon flow rate do not adequately characterize thermosyphon heat exchangers. This is because heat transfer in thermosyphon exchangers occurs in the mixed convection, rather than forced flow, regime. A linear regression equation was developed to better predict UA using the Prandtl, Reynolds, and Grashof numbers and dimensionless parameters based on fluid properties calculated for the average hot and cold leg temperatures. 9 figs.
Date: June 1, 1998
Creator: Davidson, J.H.
Partner: UNT Libraries Government Documents Department

THERMAL OSCILLATIONS IN LIQUID HELIUM TARGETS.

Description: A liquid helium target for the high-energy physics was built and installed in the proton beam line at the Alternate Gradient Synchrotron of Brookhaven National Laboratory in 2001. The target flask has a liquid volume of 8.25 liters and is made of thin Mylar film. A G-M/J-T cryocooler of five-watts at 4.2K was used to produce liquid helium and refrigerate the target. A thermosyphon circuit for the target was connected to the J-T circuit by a liquid/gas separator. Because of the large heat load to the target and its long transfer lines, thermal oscillations were observed during the system tests. To eliminate the oscillation, a series of tests and analyses were carried out. This paper describes the phenomena and provides the understanding of the thermal oscillations in the target system.
Date: July 16, 2001
Creator: WANG,L. & JIA,L.X.
Partner: UNT Libraries Government Documents Department

Majorana One-Tonne Cryostat Cooling Conceptual Feasibility Study

Description: This report evaluates the conceptual plans for a one-tonne (S4) cryostat cooling design. This document is based upon previous design work and experimental results used to evaluate the current MAJORANA DEMONSTRATOR (MJD) thermal design. A feasibility study of a cooling system for S4 based on the MJD thermosyphon experiment is presented. The one-tonne experiment will be a scaled up version of the MJD. There will be many cryostats for the S4 experiment. In this document a cryostat with up to 19 strings of Germanium crystals is analyzed. Aside from an extra outer ring of crystals, the geometry of both systems’ cryostats is very similar. The materials used in the fabrication of both ultra-low background experiments will be underground electroformed copper. The current MJD uses a two-phase liquid-gas cooling system to ensure constant operating temperature. This document presents a theoretical investigation of a cooling system for the S4 experiment and evaluates the heat transfer performance requirements for such a system.
Date: February 17, 2011
Creator: Reid, Douglas J.; Orrell, John L.; Fast, James E. & Aguayo Navarrete, Estanislao
Partner: UNT Libraries Government Documents Department

Majorana Thermosyphon Prototype Experimental Setup

Description: This report presents the experimental setup of Pacific Northwest National Laboratory’s MAJORANA DEMONSTRATOR thermosyphon prototype cooling system. A nitrogen thermosyphon prototype of such a system has been built and tested at PNNL. This document presents the experimental setup of the prototype that successfully demonstrated the heat transfer performance of the system.
Date: August 1, 2011
Creator: Reid, Douglas J.; Guzman, Anthony D. & Munley, John T.
Partner: UNT Libraries Government Documents Department

Majorana Thermosyphon Prototype Experimental Results

Description: Objective The Majorana demonstrator will operate at liquid Nitrogen temperatures to ensure optimal spectrometric performance of its High Purity Germanium (HPGe) detector modules. In order to transfer the heat load of the detector module, the Majorana demonstrator requires a cooling system that will maintain a stable liquid nitrogen temperature. This cooling system is required to transport the heat from the detector chamber outside the shield. One approach is to use the two phase liquid-gas equilibrium to ensure constant temperature. This cooling technique is used in a thermosyphon. The thermosyphon can be designed so the vaporization/condensing process transfers heat through the shield while maintaining a stable operating temperature. A prototype of such system has been built at PNNL. This document presents the experimental results of the prototype and evaluates the heat transfer performance of the system. The cool down time, temperature gradient in the thermosyphon, and heat transfer analysis are studied in this document with different heat load applied to the prototype.
Date: December 17, 2010
Creator: Fast, James E.; Reid, Douglas J. & Aguayo Navarrete, Estanislao
Partner: UNT Libraries Government Documents Department

Engineering Design Elements of a Two-Phase Thermosyphon to Trannsfer NGNP Nuclear Thermal Energy to a Hydrogen Plant

Description: Two hydrogen production processes, both powered by a Next Generation Nuclear Plant (NGNP), are currently under investigation at Idaho National Laboratory. The first is high-temperature steam electrolysis, which uses both heat and electricity; the second is thermo-chemical production through the sulfur iodine process primarily using heat. Both processes require a high temperature (>850°C) for enhanced efficiency; temperatures indicative of the NGNP. Safety and licensing mandates prudently dictate that the NGNP and the hydrogen production facility be physically isolated, perhaps requiring separation of over 100 m.
Date: July 1, 2009
Creator: Sabharwal, Piyush
Partner: UNT Libraries Government Documents Department

Solar water heating: FEMP fact sheet

Description: Using the sun to heat domestic water makes sense in almost any climate. Solar water heaters typically provide 40 to 80{percent} of a building's annual water-heating needs. A solar water-heating system's performance depends primarily on the outdoor temperature, the temperature to which the water is heated, and the amount of sunlight striking the collector.
Date: September 30, 1999
Creator: Clyne, R.
Partner: UNT Libraries Government Documents Department

Theoretical Design of Thermosyphon for Process Heat Transfer from NGNP to Hydrogen Plant

Description: The Next Generation Nuclear Plant (NGNP) will most likely produce electricity and process heat, with both being considered for hydrogen production. To capture nuclear process heat, and transport it to a distant industrial facility requires a high temperature system of heat exchangers, pumps and/or compressors. The heat transfer system is particularly challenging not only due to the elevated temperatures (up to ~ 1300K) and industrial scale power transport (=50 MW), but also due to a potentially large separation distance between the nuclear and industrial plants (100+m) dictated by safety and licensing mandates. The work reported here is the preliminary analysis of two-phase thermosyphon heat transfer performance with alkali metals. A thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. In contrast to single-phased forced convective heat transfer via ‘pumping a fluid’, a thermosyphon (also called a wickless heat pipe) transfers heat through the vaporization / condensing process. The condensate is further returned to the hot source by gravity, i.e. without any requirement of pumps or compressors. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. Two-phase heat transfer by a thermosyphon has the advantage of high enthalpy transport that includes the sensible heat of the liquid, the latent heat of vaporization, and vapor superheat. In contrast, single-phase forced convection transports only the sensible heat of the fluid. Additionally, vapor-phase velocities within a thermosyphon are much greater than single-phase liquid velocities within a forced convective loop. Thermosyphon performance can be limited by the sonic limit (choking) or vapor flow and/or by condensate entrainment. Proper thermosyphon requires analysis of both.
Date: September 1, 2008
Creator: Sabharwall, Piyush; Patterson, Mike & Gunnerson, Fred
Partner: UNT Libraries Government Documents Department