2 edition of The effect of wick geometry on the operation of a longitudinal heat pipe found in the catalog.
Heat pipe limitations. During operation, heat pipes may encounter various limitations. Common limitations that are well documented in literature [2, 3, 11, 12] are: viscous limit, sonic limit, entrainment limit, boiling limit and capillary the application of electronics cooling the most common limitation is the capillary limit .This limit is reached when the wick . Figure 6. Photo of Heat Pipe Test Bench . Figures 7, 8 and 9 show the temperature differences between. evaporator and condenser for mesh, groove and sintered. metal powder heat pipes, respectively. A heat pipe with a mesh wick structure has the largest thermal impendence. The orientation has a large effect on its heat transfer, but it.
of Flattened Heat Pipe using Three-Dimensional Finite Element Model W. Intagun, N. Kammuang-lue, P. Sakulchangsatjatai, P. Terdtoon Abstract The objective of this paper is to study the effect of pipe flattening on pressure drop in vapor core of flattened heat pipe using three-dimensional finite element model. However, the net effect was the same as if the heat pipe had dried up. "As the flooded region grew, the pipe did a poorer job of evaporating liquid, just as would happen if the heater were drying.
Modulated wick heat pipe G.S. Hwanga, M. Kavianya,*, W.G. Andersonb, J. Zuob aDepartment of Mechanical Engineering, University of Michigan, Ann Arbor, MI , United States bAdvanced Cooling Technologies, Inc., Lancaster, PA , United States Received 15 May ; received in revised form 8 September Available online 17 November Abstract In heat . Thermal Design: Heat Sinks, Thermoelectrics, Heat Pipes, Compact Heat Exchangers, and Solar Cells, Second Edition, is a significantly updated new edition which now includes a chapter on thermoelectrics It covers thermal devices such as heat sinks, thermoelectric generators and coolers, heat pipes, and heat exchangers as design components in larger systems.
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The effect of wick geometry on the operation of a longitudinal heat pipe. The wick geometries were a function of the wire mesh size and the total wick thickness.
A nickel heat pipe was built and operated using both water and ethyl alcohol as the working fluids. The different wick materials used were 50 mesh, 80 mesh, and mesh, plain Author: Hugh Edward Jr.
Kilmartin. Enter the password to open this PDF file: Cancel OK. File name:. Heat pipe components – principally the wick, working fluid and wall material – have to be carefully selected for compatibility with one another over the appropriate operating temperature range.
Such considerations lead to successful operation for the design life of the unit. A novel experimental approach is developed for characterizing the performance of heat pipe wick structures.
This approach simulates the actual operation of wick structures in a heat pipe. Open, partially submerged, sintered copper wicks of varying pore size are studied under the partially saturated conditions found in normal heat pipe operation.
Minimum capillary radius: This parameter should be small if a large capillary pressure difference is required, such as in terrestrial operation for a long heat pipe with the evaporator above the condenser, or in cases where a high heat transport capability is needed. Permeability: Permeability is a measure of the wick resistance to axial liquid.
For the heat pipe designs, which have found the widest application, versus the classical capillary-wick heat pipes and the wickless heat pipes or closed two-phase thermosyphons, mathematical. Wick in heat pipe ensures liquid returns from the condensation section to the evaporation section of heat pipe and therefore the wick heat pipe can operate at various tilt angles, even horizontally.
The deeper the tilt angle is from vertical, the greater the decrease in heat pipe performance. The capillary effect describes the limitation of the wick to transport the working liquid to the wick in axial direction.
the Heat Pipe geometry was modelled as a solid tube where the internal. PRINCIPLES OF OPERATION. The operation of a heat pipe (Faghri, ) is easily understood by using a cylindrical geometry, as shown in Fig. However, heat pipes can be of any size or shape. The components of a heat pipe are a sealed conducted through the pipe wall and wick structure, where it vaporizes.
Note: Unless otherwise indicated heat pipe diameter is circular. Figure 3. Measured heat pipe performance limits as a function of geometry, wick and vapor limits. Bending. Bending the heat pipe will also affect the maximum power handling capacity, for which the following rules of thumb should be kept in mind.
where is the rate of heat transfer, η l the liquid viscosity, A w the cross sectional area within the wick, K the permeability of the wick, and ρ l the liquid density.
The gravitational head (ρ l gl cosΦ) may be positive or negative, depending on whether the pipe is gravity assist or working against gravity (see Figure 1).
In calculating the vapor pressure drop (Δp v) it is important to. The operation of a heat pipe is easily understood by using a cylindrical geometry, as shown in Fig. However, heat pipes can be of any size or shape. The components of a heat pipe are a sealed container (pipe wall and end caps), a wick structure, and a small amount of working fluid which is in equilibrium with its own vapor.
employed to determine the condensing limit of a wickless heat pipe, rotating about its longitudinal axis. Performance characteristics including the effects of geometry, rotational speed, and the characteristics of fluid are given.
A comparison is made between the condensing, boiling, sonic, and entrain-ment limits for a given heat pipe geometry. The graph also shows that if the heat pipe is operated against the force of gravity, the liquid undergoes a larger pressure drop. The result is less pumping of the wick with reduced heat transfer.
The amount of heat transfer decrease depends on the particular heat pipe. A typical heat pipe is made of the following. the heat pipe are the surface tension, evaporation enthalpy and the viscosity of the liquid, as higher Me as better is the heat pipe. PROJECT DESCRIPTION By means of knowledge about the theory of heat pipes, one is now able to carry out a basic calculation of a heat pipe.
Beginning with a definition of the problem, including the temperature. International Heat Pipe Conference inregarding operating conditions, Dr. Polasek stated that the“For successful operation of an oscillating heat pipe, liquid plugs and vapor bubbles must coexist inside the capillary tube along its length.
This can be achieved by vacuuming the tube and then partially filling it with a working fluid. Fig Internal Flow structure of heat pipe. different. In loop heat pipe (LHP), wick is limited to the. HEAT PIPE HEAT EXCHANGER (HPHE) Theoretical studies.
Wan et al. () theoretically investigated the effect of a loop heat pipe. A the wick structure of a heat pipe includes a woven mesh curled to be located inside a tubular member of the heat pipe, and a plurality of fiber bundles longitudinal attached to an interior surface of the tubular member and sandwiched between the woven mesh and the tubular member.
The fiber bundle provides capillary action in the longitudinal direction, and the. together under the same condenser and evaporator conditions. One heat pipe with bronze wick of(X)screen mesh and the other one with copper wick of (X)screen mesh.
This case was used to examine the thermal conductivity effect on the heat pipe operation. Heat pipes are used in a wide range of applications, including electronics cooling, die-casting and injection moulding, heat recovery and energy conservation, de-icing and manufacturing process temperature control, and in domestic appliances.
An essential guide for practicing engineers and an ideal text for postgraduate students, the book takes a highly practical approach to the.
The heat pipe must also withstand bonding temperatures. Design a heat pipe to meet this specification. Selection of materials and working ﬂuid The operating conditions are contained within the specification. The selection of wick and wall materials is based on the criteria discussed in Chapter 3.
As this is.Heat pipe wick structures are constructed from various materials and methods. The most common heat pipe wick structures include: axially grooves on the inner heat pipe vessel wall, screen/wire and sintered powder metal.
Other advanced heat pipe wick structures include arteries, bi-dispersed sintered powder and composite wick structures.length of a flat plate heat pipe when a strip heater is partially covering the evaporator section.
Huang and Liu () developed an analytical model to calculate the liquid flow field with localized heating condition and also examined the effect of the location and the geometry of the heater on the heat pipe performance.
Leong et al. (