The hybrid method for the plate-finned tube evaporator design process

Abstract

The plate-finned tube evaporator performance, in terms of heat transfer rate and refrigerant pressure drops, is influenced by several choices done during the design process to be carried out complying with different constraints. In this paper different refrigerant circuitry layout options together with other parameters variations were investigated with the purpose of supporting designers. Performance predictions were calculated using the hybrid method as well as appropriate Performance Evaluation Criteria (PEC) were adopted to select the best layout. The hybrid method has been here revised and improved aiming at modelling heat exchangers with an approach closer to real configurations that include complex circuit layouts. The method was chosen as its main advantage (high accuracy in the results with low computational costs) allowed to easily perform operating conditions modifications to be compared.

Fin and Tube HVAC Evaporators Design by the Hybrid Method

“…The properties in the border cells are calculated independently. The heat Schematic representation of the evaporator by a three dimensional matrix [16].…”

“…Then, Starace et al [13] applied the method to a plate-finned evaporator with a simple refrigerant circuit configuration that was organized into independent rows and fed uniformly at the top of the exchanger. Moreover, Starace et al [14] achieved progress in the development of the hybrid technique by applying it on evaporators with complex circuit layouts to assess the impact of circuitry configuration on the overall performance in terms of heat transfer rate and refrigerant pressure decreases. Afterward, the hybrid approach algorithm underwent additional modifications to make it even more adaptable and compatible with real heat exchangers [15].…”

Improvements to the hybrid method applied to the design of plate-finned tube evaporators

“…Then, other tests were performed considering different refrigerants and varying the conditions of the fluids at the inlet [9]. The results show that all tested refrigerants (R134a, R410a, R32, R404a, R507a, R1234yf, R1234ze) behave in the same way concerning the variation in the number of circuits.…”

“…Other tests performed with R134a on different circuitry arrangements at the same heat transfer rate showed that an 8-circuits configuration can be chosen to reduce the refrigerant pressure drop of 45.3% and so operating costs, by increasing the refrigerant flowrate of 314% while maintaining the same performance in terms of heat transfer rate. More investigations performed on other circuitry layouts showed that the air inlet side does not significantly influence the performance of the HX in terms of heat transfer rate [9]. In addition, other tests showed that a fine optimization of the refrigerant path at a same number of circuits is possible, but the benefit in terms of increased performance is very small [9].…”

“…More investigations performed on other circuitry layouts showed that the air inlet side does not significantly influence the performance of the HX in terms of heat transfer rate [9]. In addition, other tests showed that a fine optimization of the refrigerant path at a same number of circuits is possible, but the benefit in terms of increased performance is very small [9].…”