JPS5812050Y2 - Plate heat exchanger - Google Patents

Description

[Detailed description of the invention] The present invention relates to a plate heat exchanger, and its purpose is to minimize the number of plates and optimize the number of plates without being dominated by the small flow rate fluid of the two fluids being heat exchanged. It is intended to provide a plate configuration.

In conventional plate heat exchangers, the flow paths for both high-temperature and low-temperature fluids have the same shape, so if both fluids flow at equal flow rates into the plate, the film heat transfer coefficients of the two fluids will vary depending on the liquid quality. They are different, but they are almost the same.

That is, a high heat transfer coefficient can be obtained without one of the film heat transfer coefficients dominating the overall heat transfer coefficient.

For example, if the flow rates of the high temperature fluid 1 and the low temperature fluid 2 are equal, the heat transfer coefficients of both fluids will be made equal by creating completely opposing flows as shown in FIG. 1a.

However, if there is a difference in the flow rates of the high-temperature fluid and the low-temperature fluid, it is necessary to change the combination of plates as shown in Figure 1 and make the number of passes in the small flow channel more than one to form partially parallel flow. Efficiency decreases.

By providing part of the parallel flow in this manner, the flow rates in the plate flow path can be made equal.

When there is a flow rate difference between the two fluids in this way, if you try to match the film heat transfer coefficient to the high flow rate fluid, due to the plate flow path configuration, it may not necessarily be possible to flow completely in opposite directions depending on the specification conditions, and the flow may be partially opposite. A situation occurs in which incomplete states, parallel flow parts, and parallel flow parts coexist.

Usually, the general heat transfer formula used is q = U-A-Jtm (q = heat exchange amount, U = overall heat transfer coefficient, A - heat transfer area, Jtm = temperature difference), and in the case of the above-mentioned completely opposite flow, the logarithmic average Temperature difference (J
tm) does not require correction, that is, the correction value (Ft) is 1
．． 0, and the correction value (F,
) was an intermediate value between 0 and 1.0, which meant that a lower temperature difference could not be achieved compared to the case of complete counterflow, and as a result, the heat transfer area had to be increased.

The present invention solves the above-mentioned drawbacks by inserting a flow path change adjustment part 3 at an appropriate position in the flow path on the small flow rate side of the two fluids. Reverse the side flow direction by 180°.

On the other hand, the large flow fluid side is only allowed to pass through, and the fluid flow direction is not changed.

What is shown in FIG. 4 is an embodiment of the flow path change adjustment section 3, in which the flow path is changed by providing two play plates 4 in the flow path on the small flow rate fluid side. The figure shows an example in which a partition plate 5 is provided as the flow path change adjustment section 3 and the flow path is changed through a conduit 6.

Note that the partition plate 5 only needs to have a fluid passage, and the conduit 6 can be omitted.

As described above, in the present invention, by reversing the flow direction of the small flow rate fluid side, the flow directions of the two fluids can be made to be completely opposite flows.

Therefore, since the logarithmic average temperature difference between the two fluids takes on a value of substantially completely opposite flow, it is possible to obtain the optimum plate configuration with the minimum number of plates without being dominated by the one flow rate fluid side as mentioned above.

[Brief explanation of the drawing]

Figures 1a and 1b are front views showing the flow path configuration by plates;
FIG. 2 is a front view of a flow path configuration showing one embodiment of the present invention, FIG. 3 is a front view showing another embodiment, and FIGS. 4 and 5 are enlarged sectional views of a flow path change adjustment section. 1.2... Two fluid flow paths for heat exchange, 3...
...Flow path change adjustment section, 4... Play plate, 5...
...Partition plate, 6... Conduit.

Claims (3)

[Scope of utility model registration request] (1) A plate heat exchanger is constructed by stacking and tightening multiple heat transfer plates through gaskets, and a flow path change adjustment section is inserted into the flow path on the low flow rate side of the two fluids to be heat exchanged. A plate heat exchanger characterized in that the two fluids are caused to flow in completely opposite flows. (2) As a flow path change adjustment section provided in the flow path on the small flow rate side,
A plate heat exchanger according to claim (1) of the utility model registration, in which two plates are inserted as play plates. (3) As a flow path change adjustment section provided in the flow path on the small flow rate side,
A plate heat exchanger according to claim (1) of the registered utility model, in which a partition plate having a conduit is inserted.