Application food heat pdf pipe

Heat pipes are also used to recover energy as heat exchanger between supply and exhaust air streams. With no moving parts and no tilt mechanism needed, HPT energy recovery modules have a distinct advantage over the competitors and other technologies. HPT's advances in heat pipes have opened many large markets with a wide variety of applications. The commercial and industrial applications include, but are not limited to, medical and health facilities, data centers, schools, supermarkets, restaurants, libraries and archives, warehouses, hotels, public and commercial buildings, and high-tech facilities.

In , the company began designing and installing commercial heat pipe systems used for dehumidification and passive cooling. Early installations included cooling systems for government radar and satellite tracking stations, heat recovery for buildings using outside air, and resolution of building humidity problems.

By , the company had discovered the huge market that exists for commercial HVAC dehumidification systems. The company began performing market research and working closely with a number of utility companies, specifying engineers, and national restaurant chains to install, test and monitor the heat pipes.

The results were very favorable and the technology became the centerfold of numerous presentations at workshops and seminars.

Since then, the growth of heat pipe acceptance has become apparent with numerous installations. There are many applications for the company's patented technology. Commercial markets are extremely receptive to the dehumidification products and heat recovery products. Heat pipes are the most effective passive method of transferring heat available today. In their simplest form, a heat pipe is a sealed tube containing a phase-change fluid.

The heat pipes for HVAC applications are usually made of copper tubes, aluminum fins.. Different working fluids are used to suit various temperature ranges.

In the case of heat pipes for HVAC applications, commercially available refrigerants are normally used as the working fluid. When there is temperature difference in two air streams of each end of the heat pipes, hot air stream applied to one end of the heat pipe, heat boils the inside fluid causing it to change phase from liquid to gas. This vaporization process absorbs large amounts of heat from hot the air stream. Vapor then travels to the other end of the heat pipe, where another air stream with the lower temperature causes the working fluid to condense and release the heat to the cold airflow.

Fluid return is normally accomplished by gravity. The constant circulation of evaporating and condensing of the working fluid is the principle of heat pipes heat transfer. Passive HPT heat pipes do not need a circulating pump to operate and have no operating cost except for a nominal increase in static pressure. They have no moving parts to malfunction or to be maintained.

Below illustrations show how wrap around heat pipes replace the old overcool then reheat method used to extract more moisture from an air stream. In the case of the wrap around heat pipes, all reheat energy is site recovered. Moreover, the reheat is captured from incoming air stream, thus reducing the load on the cooling coil.

Heat Pipe Principle and Applications. The Heat Pipe Principle Having first been invented near the turn of the 20th century, the heat pipe is not in itself a new invention. Recent Heat Pipe Development Modern heat pipes are able to transfer heat several hundred times faster than a solid copper rod.

Opportunities in Commercial Applications There are many applications for the company's patented technology. Heat Pipes for Dehumidification and Heat Recovery Overview Heat pipes are the most effective passive method of transferring heat available today.

Heat pipes can transfer heat with minimal temperature difference between one end and the other. Basic Heat Pipe Structure Diagram A traditional heat pipe is a hollow cylinder filled with a vaporizable liquid.

Knuckle Joint A knuckle joint is used to connect two rods which are under the action of tensile loads. However, if the joint is guided, the rods may support a compressive load. A knuckle joint Skip to content Home - Blog - Thermal Engineering. Table of Contents. The heat pipe is a device having a high thermal conductance which utilizes the transport of a vapour and rejection of latent heat to achieve efficient thermal energy transport.

The theory of heat pipes is well developed. Their use in applications involving temperatures in the cryogenic regime, and with development units running as high as degrees C, shows that they can function over a large part of the temperature spectrum.

Applications in spacecraft, electronics and die casting are but few of the uses for these devices. A heat pipe is a device that efficiently transports thermal energy from its one point to the other.

It utilizes the latent heat of the vaporized workingfluid instead of the sensible heat. As a result, the effective thermal conductivity may be several orders of magnitudes higher than that of thegood solid conductors.

A heat pipe consists of a sealed container, a wick structure, a small amount of working fluid that is just sufficient to saturate the wick and it is in equilibrium with its own vapor.

The operating pressure inside the heat pipe is the vapor pressure of its working fluid. The length of the heat pipe can be divided into three parts viz. The three basic components of a heat pipe are :. The container. The working fluid. The wick or capillary structure. The function of the container is to isolate the working fluid from the outside environment.

It has to therefore be leak-proof, maintain the pressure differential across its walls, and enable transfer of heat to take place from and into the working fluid. Selection of the container material depends on many factors. These are as follows:. Most of the above are self-explanatory. A high strength to weight ratio is more important in spacecraft applications.

The material should be non-porous to prevent the diffusion of vapor. A high thermal conductivity ensures minimum temperature drop between the heat source and the. A first consideration in the identification of a suitable working fluid is the operating vapour temperature range. Within the approximate temperature band, several possible working fluids may exist, and a variety of characteristics must be examined in order to determine the most acceptable of these fluids for the application considered.

The prime requirements are:. The selection of the working fluid must also be based on thermodynamic considerations which are concerned with the various limitations to heat flow occurring within the heat pipe like, viscous, sonic, capillary,entrainment and nucleate boiling levels. It is a porous structure made of materials like steel, alumunium, nickel or copper in various ranges of pore sizes.

They are fabricated using metal foams, and more particularly felts, the latter being more frequently used. By varying the pressure on the felt during assembly, various pore sizes can be produced. By incorporating removable metal mandrels, an arterial structure can also be molded in the felt. Fibrous materials, like ceramics, have also been used widely. They generally have smaller pores. The main disadvantage of ceramic fibres is that, they have little stiffness and usually require a continuos support by a metal mesh.

Thus while the fibre itself may be chemically compatible with the working fluids, the supporting materials may cause problems. More recently, interest has turned to carbon fibres as a wick material. Carbon fibre filaments have many fine longitudinal grooves on their surface, have high capillary pressures and are chemically stable.

A number of heat pipes that have been successfully constructed using carbon fibre wicks seem to show a greater heat transport capability. The prime purpose of the wick is to generate capillary pressure to transport the working fluid from the condenser to the evaporator.

It must also be able to distribute the liquid around the evaporator section to any area where heat is likely to be received by the heat pipe. Often these two functions require wicks of different forms.