Measuring Selected Parameters of Polypropylene Fibre Heat Exchangers (original) (raw)
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Non-typical designs of Polypropylene Capillary Heat Exchangers
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Materiali in tehnologije, 2020
The article presents potential applications of fibres made of polypropylene in new types of heat exchangers. It describes the properties of polypropylene and the method of sealing fibres in the potting process. An analysis was carried out to calculate the thermal capacity and pressure loss of the exchanger. An experimental stand was used to examine the heat transport in a shell-and-tube exchanger in a counter-flow setup. Measurements were carried out with several designs of this type of exchanger comprising transparent as well as porous fibres. The experiment confirmed that transparent fibres in an exchanger provide heat transfer that is 20 % better than that of the porous fibres. In the case of an exchanger comprising 1400 transparent fibres with an outer diameter of 0.275 mm, the overall heat-transfer coefficient k, at a flow rate of secondary water of 150 L•h-1 , was found to be 603 W•m-2 •K-1. With the use of "whirlers" on the outer side of fibres, the k value elevated to 933 W•m-2 •K-1 , and at a flow rate of 200 L•h-1 , the heat-transfer coefficient amounted to as much as 1191 W•m-2 •K-1. Keywords: polypropylene fibres, heat exchanger, experimental research, heat transfer V~lanku je predstavljena mo`nost uporabe vlaken, izdelanih iz polipropilena v novih tipih toplotnih izmenjevalnikov. Opisuje lastnosti polipropilena in na~in pritrditve vlaken v postopku t. i.: potting-a. Analiziran je izra~un toplotne mo~i izmenjevalnika in izguba tlaka v izmenjevalniku. Na stojalu za eksperimente je bil preverjen prenos toplote pri izmenjevalniku tipa Tube and Shell v protito~ni povezavi. Izmerili smo ve~konstrukcij tega tipa s prozornimi in poroznimi vlakni. Poskus je potrdil, da prozorna vlakna v izmenjevalniku v primerjavi s poroznimi vlakni zagotavljajo bolj{i prenos toplote za do 20 %. Za izmenjevalnik s 1400 prozornimi vlakni z zunanjim premerom 0,275 mm, je bil pri pretoku sekundarne vode 150 L•h-1 dolo~en koeficient prenosa toplote k 603 W•m-2 •K-1. Pri uporabi turbulatorjev" na zunanji strani vlaken se je vrednost k pove~ala na 933 W•m-2 •K-1 , pri pretoku 200 L•h-1 pa je vrednost koeficienta prenosa toplote dosegla 1191 W•m-2 •K-1. Klju~ne besede: polipropilenska vlakna, izmenjevalnik toplote, poskusne raziskave, prenos toplote
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