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FOULING OF POLYMERIC HOLLOW FIBER HEAT EXCHANGER BY ASHRAE 52.1 TEST DUST

článek ve sborníku mimo WoS a Scopus

en

Thermal effectiveness of heat exchangers working in contaminated conditions is negatively affected by fouling. Considering HVAC-R (heating, ventilation and air conditioning) or automotive applications, outdoor or domestic dust can be defined as main source of fouling. The heat exchanger made of polymeric hollow fibers was designed and tested in conditions typical for indoor fancoil operation, namely room temperature air (20 °C) flowing through the hot water coil (water inlet 50 °C) with low velocity (1.5 m/s). ASHRAE test dust was used as recommended type of foulant to model domestic dust presence. It was found that the ASHRAE Dust 52.1 has a very significant impact on the pressure drop and heat transfer. Air-side pressure drop rises 191% and overall heat transfer coefficient decreased to 62% for a dust injection of 250g (4000 g/m2). Decrease of heat transfer rate of heat exchanger was influenced mainly by clogging the frontal area because the first layers were significantly more than deeper layers. Such kind of fouling does not cover the surface uniformly but excludes significant part of surface from the heat transfer process because air cannot flow through the clogged part. Furthermore, detailed macro photographs were obtained under all conditions tested to more fully characterize the particulate deposition.

Thermal effectiveness of heat exchangers working in contaminated conditions is negatively affected by fouling. Considering HVAC-R (heating, ventilation and air conditioning) or automotive applications, outdoor or domestic dust can be defined as main source of fouling. The heat exchanger made of polymeric hollow fibers was designed and tested in conditions typical for indoor fancoil operation, namely room temperature air (20 °C) flowing through the hot water coil (water inlet 50 °C) with low velocity (1.5 m/s). ASHRAE test dust was used as recommended type of foulant to model domestic dust presence. It was found that the ASHRAE Dust 52.1 has a very significant impact on the pressure drop and heat transfer. Air-side pressure drop rises 191% and overall heat transfer coefficient decreased to 62% for a dust injection of 250g (4000 g/m2). Decrease of heat transfer rate of heat exchanger was influenced mainly by clogging the frontal area because the first layers were significantly more than deeper layers. Such kind of fouling does not cover the surface uniformly but excludes significant part of surface from the heat transfer process because air cannot flow through the clogged part. Furthermore, detailed macro photographs were obtained under all conditions tested to more fully characterize the particulate deposition.

Hollow fiber, plastic heat exchanger, particulate fouling, test dust

30.08.2017

Heat Exchanger Fouling and Cleaning XI - 2017