Untitled record

(54) Name: Heat exchanger with honeycomb structure

7509010-0

The present invention relates to a heat exchanger with a honeycomb structure. A heat exchanger with honeycomb structure is usually made of wavy plates and flat boards, which are stacked on one another for a sandwich construction. The conventional wavy and flat sheets are made of aluminum foil, cellulose paper or asbestos paper.

The heat exchanger made of aluminum foil was effective only with respect to sensible heat_}and the corrosion resistance was not sufficient.

The heat exchanger made from cellulose paper was effective in both sensible and latent heat. The cellulose paper was not satisfactory in terms of thermal stability and corrosion resistance. The cellulose paper was soaked as it absorbed water.

The asbestos paper heat exchanger was effective in both sensible and latent heat and had high thermal stability and high corrosion resistance. However, there is a high risk that the asbestos dust emitted from the heat exchanger will adversely affect the human body.

It is therefore an object of the invention to provide a heat exchanger with honeycomb structure which is effective in both sensible heat and latent heat. Another object of the invention

7509010-0 is to provide a honeycomb structure heat exchanger which has high thermal stability and high corrosion resistance. Yet another object of the invention is to provide a honeycomb structure heat exchanger made of wavy and flat sheets of high temperature resistant nylon paper. Yet another object of the invention is to provide a heat exchanger with honeycomb structure which has a long life.

The characterization of the heat exchanger according to the invention is apparent from the claims.

The advantages and features of the invention will become more apparent from the following detailed description. The detailed description and specific examples refer to only preferred embodiments of the invention as exemplary for illustrative purposes, and many modifications and modifications are possible within the scope of the inventive idea which will be apparent to those skilled in the art upon a study of the detailed description.

The invention will be described below in connection with the accompanying drawings, which are given by way of example only and which do not limit the invention.

Fig. 1 is a perspective view showing a typical structure of a honeycomb heat exchanger.

Fig. 2 is a front view showing another type of heat exchanger with honeycomb structure.

Figures 3 and 4 are diagrams showing the contraction model 25 as a function of the heating period of a honeycomb structure with a honeycomb structure according to the invention.

In order to facilitate a fuller understanding of the invention, a typical design of a honeycomb heat exchanger should first be described with reference to Figures 1 and 2.

The honeycomb structure heat exchanger comprises flat disks 1 or 1 'and wavy skis 2 or 2', which are stacked into a sandwich structure. Fig. 1 shows a cross-type honeycomb heat exchanger and Fig. 2 shows a counter-current honeycomb heat exchanger.

The flat and wavy sheets of the embodiment are made of high temperature resistance nylon paper, e.g. NOMEX (manufactured by Du Pont).

Conventional nylon is made from adipic acid and hexamethylenediamine, these substances being two-dimensional polycondensated with an amino groups. In contrast, nylon paper with high temperature resistance comprises aromatic compounds and the above-mentioned substances are condensed three-dimensionally.

The high temperature resistance nylon paper is bent using a weighing machine to form the wavy sheets, as is well. known in the art, and then the flat and wavy slices are stacked on top of one another for a sandwich construction.

The temperature resistant nylon paper has very high temperature resistance compared to conventional nylon paper, and the high temperature nylon paper can hold very large amounts of water, because it is a porous construction. Therefore, the heat exchanger made of nylon paper with high temperature resistance is effective not only for sensible heat but also for latent heat.

The following table shows a comparison of the characteristic values ​​between high temperature resistance nylon paper (NOMEX) and asbestos paper.

<td></td><td>maximum admissible temperature</td><td>Specifically heat cal / ° C</td><td>Specific weight</td><td>Thermal con- conductivity Kcal / mh, ° C</td>

<td>Asbestos- paper</td><td>500 ° C</td><td> 0,27</td><td>OO O</td><td> 0,3 - 0,4</td>

<td>NOMEX</td><td>220 ° C</td><td> 0,29</td><td> 0,27</td><td> 0,94</td>

The table shows how the specific heat for NOMEX is next: identical to the corresponding value for asbestos paper, while the specific weight for NOMEX is substantially less. This results in high temperature resistance nylon paper being suitable for latent heat exchangers, since the high temperature resistance nylon paper heat exchanger has significantly lower heat capacity.

When the heat transfer heat exchanger is used to obtain dry air, the wavy and flat sheets are impregnated with hygroscopic substances, thereby dehumidifying the air passing through the heat exchanger. The hygroscopic substances are regenerated after the dehumidification operation by absorbing heat energy. The required heat energy is determined by the total heat capacity of the hygroscopic substances and the heat transfer heat exchanger. The heat transfer heat exchanger of the present invention is very effective for dehumidification operations due to its low heat capacity. When the wavy and flat sheets are made of porous organic film, porous organic nonwoven material, porous organic paper or nylon paper with high temperature resistance, the heat exchanger can be used with good effect for dehumidifying the air.

In this case, the wavy and the flat sheets are impregnated with a hygroscopic salt, e.g. lithium chloride. It is necessary to heat the hygroscopic salt to about 100-150 ° C to regenerate the substances. Therefore, the heat exchanger performs the dehumidification operation at room temperature and is regenerated at a substantially higher temperature. The heat exchanger expands at room temperature, while it coalesces at a substantially higher temperature. The expansion movement becomes smaller after repeated cycles, so the dimensions of the heat exchanger become smaller after repeated cycles. In particular, when the heat exchanger is of a rotary type, the contraction in the axial direction causes leakage of the air flow to occur, thereby greatly affecting the performance of the heat exchanger.

Fig. 3 shows the relationship between the working time period indicated along the abscissa axis and the contraction module, which is indicated along the ordinate axis, for a countercurrent type rotary heat exchanger, the regeneration being performed at 180 ° C.

It can be seen from Fig. 3 that the contraction module reaches the value 4.5% after 1000 hours of operation. When, for example, the axial length of the heat exchanger is 1000 mm, the heat exchanger has a length of 955 mm after 1000 hours of operation. This is not appropriate in view of the air flow conditions.

The moisture is kept in the gaps between the fibers during the dehumidification operation and the fibers move during the heating operation, and therefore the heat exchanger is contracted upon repeating the regeneration cycle.

In order to avoid the aforementioned inconveniences, it is necessary to fix the fibers close to one another to thereby prevent the movement of the fibers during the regeneration operation without reducing the hygroscopic effects.

For this purpose, the wavy and flat sheets are impregnated with silica sol as follows.

The heat exchanger, which comprises the wavy and stacked wafers stacked on top of each other in a sandwich construction

7509010-0 high temperature resistance nylon paper, held at about 200 ° C for several hours to sufficiently dry the heat exchanger. This drying operation serves to remove an initial contraction. After the heat exchanger is cooled to room temperature, the heat exchanger is impregnated with silioasol, the concentration of which is below 30% by weight, whereby the concentration of silioasol in the heat exchanger is controlled below 100% by weight, the excess silioasol is blown off using compressed air. Thereafter, the heat exchanger is kept in a dryer held at 200 ° C to evaporate the moisture, the heat exchanger being kept in the dryer for a sufficient period of time to effect siloxane bonding. In this way, a corrosion resistant device is completed.

Fig. 4 shows the relationship between the working time period indicated along the abscissa axis and the contraction module, indicated along the ordinate axis, for the heat exchanger when it is regenerated at a temperature of 180 ° C and caused to perform the dehumidification operation at a temperature of 25 ° C. . In Fig. 4, A represents the curve of a heat exchanger that has not been treated for corrosion resistance, and B represents the curve of a heat exchanger treated to achieve corrosion resistance.

It can be seen from Fig. 4 that the contraction module of a heat exchanger, whose discs are impregnated with silio sol, is very small.

A heat exchanger, which includes sheets impregnated with silioasol, has the following advantages:

1st The siloxane bond cannot be damaged even if the heat exchanger is exposed to moisture.

2nd The heat exchanger has a high temperature resistance, since the silica sol in the siloxane bond has a melting point of 1780 ° C.

3rd The heat exchanger becomes rigid through the impregnation with silioasol.

4th The handling of the heat exchanger becomes easy due to the stiffness of the heat exchanger.

It is obvious that the heat exchanger described above can be varied in many ways. Such variations do not imply any deviation from the notion of invention and all such deviations and modifications are intended to be included in the claims.

7509010-0