Advantages of using channels with different corrugation height in the plate heat exchangers

Gennadii Khavin,Tatiana Babak

doi:10.15587/1729-4061.2018.120546

Abstract

In the case when there is a difference in consumption on the side of the cold and hot heat carriers, the use of channels with the same corrugation height in one heat exchanger leads to a decrease in velocity of the heat carrier on the side with low consumption. Low velocity contributes to appearance of deposits on the heat transfer surface, which leads to disruption of operation mode of the apparatus and a forced clean-up stop. In case of using channels with a different corrugation height (cross-section area), velocities in the channels are aligned and intensity of emergence and growth of contamination falls sharply. It also allows us to reduce the heat transfer surface area of the apparatus and fully implement permissible pressure losses on the sides of the heat exchanger. For designing of heat exchangers of this structure, the authors developed the mathematical model that allows making calculations of heat exchangers for assigned operation conditions with the use of geometrical data of the plates, thermophysical properties of heat carriers and criterial equations for plates of the selected type. The calculation algorithm involves determining of the ratio between corrugation heights. Practical value lies in the fact that the proposed approach makes it possible to extend the service life of the heat exchanger prior to a maintenance stop. This enables provision of continuity of the technological process and decreases operation costs. Calculation of the heat exchanger of hot water supply by the parallel scheme of attachment to heating networks and the heat exchanger of stage 1 of the two-stage hybrid scheme was presented. Calculation data indicate a decrease in the heat transfer surface area compared to heat exchangers with channels of equal height, full realization of pressure losses and their alignment in the channels, which facilitates an increase in resistance to contamination of the plates’ surface. Calculation showed the advantage of using apparatuses with channels of different cross-section area. The higher the ratio between consumption of heat carriers in the channels, the stronger this advantage.

Highlights

Plate heat exchangers (PHE) have the same corrugation on the heating and heated sides of heat carriers. This is determined by their designs, special features of plates manufacturing, cost of creation and implementation in industry of plates with new geometric parameters and developed mathematical models for their design
Experimental and numerical study of heat transfer and pressure losses was presented in paper [7], for plates with corrugation angle of 30°, experiments were performed for different values of channel height at a fixed corrugation height on one of the heat carriers
The ratio, enabling us to calculate in advance the values of corrugation height at the design stage in every specific application, was obtained

Summary

Introduction

Plate heat exchangers (PHE) have the same corrugation on the heating (hot) and heated (cold) sides of heat carriers. 1/8 ( 91 ) 2018 when according to energy recovery conditions, there is a significant difference between consumption of the hot and cold heat carriers In this case, when providing for heat transfer requirements, temperature mode of operation and satisfying conditions for loss of pressure in the apparatus, velocity in the channels of a heat exchanger drops sharply on the side of a heat carrier with lower consumption. The same picture is observed in the case when one of the heat carriers has significantly higher viscosity than another, which requires designing a large number of channels to satisfy conditions for loss of pressure in the apparatus This leads to a significant decrease in velocity of heat carrier on the other side of the heat exchanger with all the ensuing consequences

Literature review and problem statement

Findings

The aim and objectives of the study