Abstract
An experimental study of the effects of various factors (fin pitch, fin arrangement, air temperature, air humidity, and air velocity) on the frost growth and thermal performance of a fin-tube heat exchanger has been conducted under the frosting condition. It is found that the thermal performance of a heat exchanger is closely related to the blockage ratio of the air flow passages due to the frost growth. The maximum allowable blockage ratio is used to determine the criteria for the optimal operating conditions of a fin-tube heat exchanger. It is also shown that heat transfer rate of heat exchanger with staggered fin arrangement increases about 17% and the time required for heat transfer rate to reach a maximum value becomes longer, compared with those of an inline fin-tube heat exchanger under the frosting condition. The energy transfer resistance between the air and coolant decreases with the increase of inlet air temperature and velocity and with decreasing inlet air humidity.
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Abbreviations
- A :
-
Heat transfer area, m2
- a :
-
Flow area, m2
- BR :
-
Blockage ratio, %
- C p :
-
Specific heat at constant pressure, kJ/kg°C
- D :
-
Diameter, m
- i :
-
Enthalpy, kJ/kg
- L H :
-
Latent heat, kJ/kg
- m :
-
Mass, kg
- m :
-
Mass flow rate, kg/s
- q :
-
Heat transfer rate, kW
- R :
-
Energy transfer resistance, °C/W
- S :
-
Spacing, mm
- T :
-
Temperature, °C
- t :
-
Time, s or hr
- V :
-
Volume, m3
- w :
-
Specific humidity, kg/kg′
- X :
-
Thickness, m or mm
- σ:
-
Density, kg/m3
- a :
-
Air
- av :
-
Average
- c :
-
Coolant
- F :
-
Fin
- f :
-
Forst
- i :
-
Inlet
- inl :
-
Inline fin arrangement
- l :
-
Latent
- max :
-
Maximum
- o :
-
Outlet, outer
- s :
-
Sensible
- stg :
-
Staggered fin arrangement
- T :
-
Total
- t :
-
Tube
References
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Lee, KS., Kim, WS. The effects of design and operating factors on the frost growth and thermal performance of a flat plate fin-tube heat exchanger under the frosting condition. KSME International Journal 13, 973–981 (1999). https://doi.org/10.1007/BF03184764
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DOI: https://doi.org/10.1007/BF03184764