Comparison of the Efficiency of Two Types of Heat Exchangers with Parallel Plates Made of Varied Materials

Abstract

The paper discusses two mathematical models for the air flow through a plate heat exchanger with parallel plates. The first exhausts the used air and then supplies the fresh air. The second exhausts the used air above the plate and simultaneously supplies fresh air under it (counter-flow exchanger). In both cases, the exhaust air heat is used to heat the supply air. The purpose of the research is to verify which exchanger uses the exhaust air heat more efficiently. The method of the Trefftz function was used to determine approximate solutions of the analysed problems. The results obtained for 1.2 mm thick steel, aluminium, and copper plates and for external winter, summer, and spring–autumn temperatures are discussed. The results indicate that steel is the best material for a plate heat exchanger, and the counter-flow exchanger is more efficient of the two. Thanks to the use of thin steel plates and the reduction of the air exchange time to a few minutes, cheap and efficient counter-flow exchangers can be obtained.

Comparison of the Efficiency of Cross-Flow Plate Heat Exchangers Made of Varied Materials

“…Because at the same time it turned out that exchangers with steel plates are the most effective, and as such have the lowest price and a small plate thickness, it is possible to produce relatively cheap and effective cross-flow exchangers with the use of a thin steel plate. A similar conclusion regarding the material for the construction of counter flow exchangers is presented in [5].…”

“…In our earlier paper, [5], we discussed various articles on the issues related to parallel plate heat exchangers and parallel airflow, but none of them dealt with the issue of temperature distribution in heat exchanger plates. The work [5] seems to be the first in which this issue was examined in plates of two types of exchangers depending on the material used for the plates. To the best of our knowledge, the problem of temperature distribution over time in a plate of a cross-flow exchanger has not been investigated so far.…”