Showing papers on "Heat exchanger published in 2007"

Heat Transfer and Hydraulic Resistance at Supercritical Pressures in Power Engineering Applications

Abstract: Mechanical and Nuclear Engineers are currently working on advanced power plants intended for implementation within the next decade. One such Generation IV concept is a supercritical, water-cooled nuclear reactor. In addition, there are already hundreds of supercritical steam generators operating worldwide in the thermal power industry. These system designs reduce emissions and lower cost by attaining high thermodynamic cycle and economic efficiency, utilizing both natural and forced circulation flows and optimizing heat exchanger and turbine layout and performance. Development, design, and successful operation of these power-generating units require knowledge of heat transfer, pressure drop, and thermalhydraulics at supercritical pressures. Demand for reliable information is high, and until now, no single book related to this topic has been published.This book brings together and integrates the results from over 500 of the latest sources from the global publications devoted to heat transfer and hydraulic resistance of fluids flowing inside channels of various geometries at near-critical and supercritical pressures. This book is of interest to nuclear and mechanical engineers in both industry and academia, who are concerned with the development and design of next-generation reactors, as well as engineers and technologists currently working with supercritical steam generators and power systems. Included with this book is a free CD containing fully linked references to help readers navigate the welath of material that is provided.

Experimental investigation of an adsorptive thermal energy storage

Abstract: A zeolite-water adsorption module, which has been originally constructed for an adsorption heat pump, has been experimentally investigated as an adsorptive thermal energy storage unit. The adsorber/desorber heat exchanger contains 13.2 kg of zeolite 13X and is connected to an evaporator/condenser heat exchanger via a butterfly valve. The flow rate of the heat transfer fluid in the adsorber/desorber unit has been changed between 0.5 and 2.0 l min−1, the inlet temperature to the evaporator between 10 and 40°C. It turned out that the higher the flow rate inside the adsorber/desorber unit the faster and more effective is the discharge of heat. However, at lower flow rates higher discharge temperatures are obtained. Storage capacities of 2.7 and 3.1 kWh have been measured at the evaporator inlet temperatures of 10 and 40°C, respectively, corresponding to thermal energy storage densities of 80 and 92 kWh m−3 based on the volume of the adsorber unit. The measured maximum power density increases from 144 to 165 kWh m−3 as the flow rate in the adsorber increases from 0.5 to 2 l min−1. An internal insulation in form of a radiation shield around the adsorber heat exchanger is recommended to reduce the thermal losses of the adsorptive storage. Copyright © 2006 John Wiley & Sons, Ltd.

Testing of an automobile exhaust thermoelectric generator in a light truck

Abstract: Testing was conducted on a prototype automobile exhaust thermoelectric generator (AETEG) installed in a 1999 GMC Sierra pick-up truck. The system consisted of the generator, its power conditioning unit, and the interfaces to the test truck's engine coolant and exhaust systems. The objective of the test was to measure the AETEG's performance and its effect on the truck systems as well as to determine which factors are important for optimizing an AETEG design. Testing was performed in a dynamometer-equipped wind tunnel at Delphi Corporation's Harrison Thermal Systems Division in Lockport, New York. The first tests established the benchmark data set. Then the prototype AETEG was installed and three configurations of the system were tested in succession: the AETEG alone, the AETEG with portions of the exhaust pipes leading to it insulated, and the AETEG with insulated upstream exhaust pipes and with a pre-cooling heat exchanger operating to lower the inlet coolant temperature to the generator. Some of the important outcomes of the tests were: insulating the exhaust and lowering the coolant temperature had a significant positive effect on the power, parasitic losses resulting from the AETEG weight and the coolant pumping power were significant but manageable, and the increased exhaust flow resistance and the additional heat load from the AETEG were not significant effects.

Assessment of boiling and condensation heat transfer correlations in the modelling of plate heat exchangers

Abstract: This paper studies refrigeration cycles in which plate heat exchangers are used as either evaporators or condensers. The performance of the cycle is studied by means of a method introduced in previous papers which consists of assessing the goodness of a calculation method by looking at representative variables such as the evaporation or the condensation temperature depending on the case evaluated. This procedure is also used to compare several heat transfer coefficients in the refrigerant side. As in previous works the models of all the cycle components are considered together with the heat exchanger models in such a way that the system of equations they provide is solved by means of a Newton–Raphson algorithm. Calculated and measured values of the evaporation and the condensation temperatures are also compared. The experimental results correspond to the same air-to-water heat pump studied in other papers and they have been obtained by using refrigerants R-22 and R-290.

Image heating device

Abstract: PROBLEM TO BE SOLVED: To provide an improved energy-saving image heating device by heating a toner image on a recording material without using a halogen heater or an infrared heater as a heat source, and to improve image quality by rapidly cooling the heated recording material. SOLUTION: The image heating device has a heating roller 11 heating the toner image on the recording material, and a cooler 16 cooling the heated recording material. The image heating device has a heat pump 50 performing heat exchange by a condenser 52 and an evaporator 54 while circulating a coolant in a compressor 51, the condenser 52, an expansion valve 53 and the evaporator 54. The condenser 52 is used for the heating roller 11 to exchange heat by circulating the coolant which is compressed by the compressor 51 and whose temperature is high in the heating roller 11. The evaporator 54 is used for the cooler 16 to exchange heat by circulating the coolant which is expanded by the expansion valve 53 and whose temperature is low in the cooler 16. COPYRIGHT: (C)2009,JPO&INPIT

Liquid submersion cooling system

Abstract: A portable, self-contained liquid submersion cooling system that is suitable for cooling a number of electronic devices, including cooling heat-generating components in computer systems and other systems that use electronic, heat-generating components. The electronic device includes a housing having an interior space, a dielectric cooling liquid in the interior space, a heat-generating electronic component disposed within the space and submerged in the dielectric cooling liquid, and a pump for pumping the liquid into and out of the space, to and from a heat exchanger that is fixed to the housing outside the interior space. The heat exchanger includes a cooling liquid inlet, a cooling liquid outlet, and a flow path for cooling liquid therethrough from the cooling liquid inlet to the cooling liquid outlet. An air-moving device such as a fan can be used to blow air across the heat exchanger to increase heat transfer.

Warm Water Cooling

Abstract: A method of providing cooled air to electronic equipment includes capturing heated air from a volume containing electronic equipment, cooling the heated air by more than fifteen degrees Celsius in an air-to-water heat exchanger, and supplying cooling water to the air-to-water heat exchanger at a temperature above a dew point temperature of the heated air.

Surface heating in relation to air temperature, wind and turbulence in an urban street canyon

Abstract: Wind and temperature measurements from within and above a deep urban canyon (height/width = 2.1) were used to examine the thermal structure of air within the canyon, exchange of heat with the overlying atmosphere, and the possible impacts of surface heating on within-canyon air flow. Measurements were made over a range of seasons and primarily analysed for sunny days. This allowed the study of temperature differences between opposing canyon walls and between wall and air of more than 15°C in summer. The wall temperature patterns follow those of incoming solar radiation loading with a secondary daytime effect from the longwave exchange between the walls. In winter, the canyon walls receive little direct solar radiation, and temperature differences are largely due to anthropogenic heating of the building interiors. Cool air from aloft and heated air from canyon walls is shown to circulate within the canyon under cross-canyon flow. Roofs and some portions of walls heat up rapidly on clear days and have a large influence on heat fluxes and the temperature field. The magnitude and direction of the measured turbulent heat flux also depend strongly on the direction of flow relative to surface heating. However, these spatial differences are smoothed by the shear layer at the canyon top. Buoyancy effects from the heated walls were not seen to have as large an impact on the measured flow field as has been shown in numerical experiments. At night canyon walls are shown to be the source of positive sensible heat fluxes. The measurements show that materials and their location, as well as geometry, play a role in regulating the heat exchange between the urban surface and atmosphere.

High power LED lighting assembly incorporated with a heat dissipation module with heat pipe

Abstract: A high power light emitting diode (LED) lighting assembly incorporated with heat dissipation module is provided. The LED lighting assembly includes a heat exchange base, at least one LED array, at least one heat pipe and a heat dissipation module. The heat exchange base includes at least one LED configuration plan for mounting of the LED array and at least a hollow part for insertion of the heat pipe. The LED array is arranged at a predetermined projecting angle at the LED configuration plane. The heat pipe includes a heated section, a cooling section and a conducting section, and contains a working fluid therein. The heat exchange base is mounted to the heated section and the heat dissipation module is mounted to the cooling section. The thermal energy generated by the LEDs is conducted from the heat exchange base to the heated section of the heat pipe, whereby allowing the working fluid in the heat pipe to be heated and vaporized, and flows, from the conducting section to the cooling section for dissipation at the heat dissipation module.

Hybrid air and liquid coolant conditioning unit for facilitating cooling of one or more electronics racks of a data center

Abstract: A hybrid air and liquid coolant conditioning unit is provided for facilitating cooling of electronics rack(s) of a data center The unit includes a first heat exchange assembly, including a liquid-to-liquid heat exchanger, a system coolant loop and a facility coolant loop, and a second heat exchange assembly, including an air-to-liquid heat exchanger, an air-moving device, and the facility coolant loop The system coolant loop provides cooled system coolant to the electronics rack(s), and expels heat in the liquid-to-liquid heat exchanger from the electronics rack(s) to the facility coolant The air-to-liquid heat exchanger extracts heat from the air of the data center and expels the heat to the facility coolant of the facility coolant loop The facility coolant loop provides chilled facility coolant in parallel to the liquid-to-liquid heat exchanger and the air-to-liquid heat exchanger In one implementation, the hybrid coolant conditioning unit includes a vapor-compression heat exchange assembly