Study of heat transfer coefficient in helical coil
A centrifugal pump was used to circulate the water from the tank to
the coil and then to the drain. The flow rate of the water was measured using a calibrated
rotameter. The coil was located inside the hot water rectangular bath with dimensions of 45,5
X 21,1 cm with no baffles. The height of the coil was 6,2 cm, the diameter of helix was 17,4
cm, the length of the tube in spiral was 4,72 m, and the internal diameter of the tube was
7,3mm and external diameter 1,1cm. The bath was heated with a Bioblock Scientific polystat
microprocessor controlled electrical resistance. The agitation system was composed by a
propeller fitted to a Heidloph Type RZR1 mixer. The speed of the agitator could be changed
with the speed reducing controller. The temperature of the bath was measured with a simple
Micro-tech electronic thermometer. The inlet and outlet temperatures of the water flowing
inside the coil were measured with a calibrated thermocouples K type, which were linked to
Testo 922 device.
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