Abstract
Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuous fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degC, variation of humidity between 70 and 100% RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m{sup 2}. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost
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Citation Formats
Fahlen, P.
Frosting and defrosting of air-coils - results from laboratory testing.
Sweden: N. p.,
1996.
Web.
Fahlen, P.
Frosting and defrosting of air-coils - results from laboratory testing.
Sweden.
Fahlen, P.
1996.
"Frosting and defrosting of air-coils - results from laboratory testing."
Sweden.
@misc{etde_414562,
title = {Frosting and defrosting of air-coils - results from laboratory testing}
author = {Fahlen, P}
abstractNote = {Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuous fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degC, variation of humidity between 70 and 100% RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m{sup 2}. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost water. The frosting process was interrupted when the air flow had decreased to 30% of the original value with a non-frosted coil. The results clearly show the advantage of demand controlled defrosting with variations in frosting time between 2 h with high humidity/high specific cooling load up to, for practical purposes, infinite frosting times with low humidity/low specific cooling load. The accumulated frost mass during one frosting cycle varied from less than 0.02 kg/m{sup 2} up to approximately 0.4 kg/m{sup 2}. 23 refs, 93 figs, 89 tabs}
place = {Sweden}
year = {1996}
month = {Dec}
}
title = {Frosting and defrosting of air-coils - results from laboratory testing}
author = {Fahlen, P}
abstractNote = {Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuous fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degC, variation of humidity between 70 and 100% RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m{sup 2}. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost water. The frosting process was interrupted when the air flow had decreased to 30% of the original value with a non-frosted coil. The results clearly show the advantage of demand controlled defrosting with variations in frosting time between 2 h with high humidity/high specific cooling load up to, for practical purposes, infinite frosting times with low humidity/low specific cooling load. The accumulated frost mass during one frosting cycle varied from less than 0.02 kg/m{sup 2} up to approximately 0.4 kg/m{sup 2}. 23 refs, 93 figs, 89 tabs}
place = {Sweden}
year = {1996}
month = {Dec}
}