engleski

BASIC SINGLE-PHASE FLOW PHENOMENA IN CHEVRON-TYPE PLATE HEAT EXCHANGERS

The paper presents the results of research concerning flow in corrugated chevron channels of plate heat exchangers. The basic flow mechanism is investigated through a number of dye based visualization tests performed on two channels with the chevron angles &#61538 ; ; =28o and &#61538 ; ; =65o under flow conditions corresponding to Re=(0.5÷300). A presence of basically two flow components has been observed whose influence on the heat transfer is dependent mainly upon the angle &#61538 ; ; but also upon the Re-number and aspect ratio b/l. Plate designs with higher values of &#61538 ; ; and b/l will yield better thermal performances and larger pressure drop. From data in the open literature it is concluded that at lower angles, &#61538 ; ; <45o, a variation of b/l does not significantly affect the thermal-hydraulic performances of the exchanger. Also, in the flow regimes at very low Re-numbers (Re<10) an increase of the angle &#61538 ; ; is of minor significance for enhancement of the heat transfer. The conclusions deduced are supported by experimental heat transfer and pressure drop data reported in the open literature. An assessment of thermal-hydraulic performances in terms of the area goodness factor indicates that care must be exercised when optimizing surfaces at a design stage since in certain flow regimes some aspect ratios at fixed angle yield too high pressure drop penalties relative to the gain in heat transfer.

plate heat exchangers; flow mechanism; heat transfer and pressure drop

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