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Analysis of the efficiency of plate heat exchangers
Aug 03, 2018

Gasket compression back elastic energy test

1. Test device and test piece

The test loading system is shown in the MTS-2.5 ton material performance tester. The test piece is a rectangular plate with a trapezoidal spacer groove cut out from the entire heat transfer plate, and the plate material is shown as 316L. The gasket material is EPDM rubber with a hardness of 80 Shore and the cross section of the gasket is a diamond shape with the main structural dimensions.

2, the test content

The test consists of two parts:

(1) At normal temperature, the gasket is simply compressed and rebounded. A gasket with a rhombic cross section was placed horizontally on a rigid plate, and the displacement of the gasket under different loads was tested by applying a compressive load to a steel cylinder (7 mm) fixed to the upper and lower clamps of the test machine. The loading rate refers to the actual assembly and operating conditions of the device, and the compression rate is controlled to 0.018 mm/s, and the rebound rate is 0.007 mm/s. This test is hereinafter referred to as simple compression rebound;

(2) The gasket is compressed and rebounded under the constraint of the trapezoidal seal groove.

A spacer having a rhombic cross section is embedded in a trapezoidal groove of a rectangular plate, and a load is applied by a steel cylinder fixed to the upper and lower jigs. Other loading conditions are the same as in the previous section. This test is hereinafter referred to as constrained compression rebound.

Analysis of test results

1, simple compression

It is assumed that the plate heat exchanger rubber gasket is a superelastic material, and the ratio of the thickness of the three main directions to the initial thickness of the gasket before compression is also referred to as a compression ratio. Synthetic formulas (1) and (2) are obtained: S=2WC=2[(WI1 I1WI2)I-WI2C I3WI3C-1] (4) Using the relationship between true stress and S, the true stress of the gasket after deformation is obtained. Expression: =-pI 2[WI1B-WI2B-1] (5) The principal stress component is: i=-p 2[WI12i-WI2-2i](i=1,2,3)(6) Equation (5) In the middle, B is the left Cauchy-Greenstrain tensor, -pI represents the hydrostatic pressure tensor, and I is the second-order unit tensor. For true stress tensor.

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