The air-side performance of three new slit fin-and-tube heat exchangers under dehumidifying conditions is reported. The effects of the number of rows of tubes, the fin pitch and the inlet relative humidity on air-side performance are reported. It is found that for type I slits, which are characterized by a small louvre angle (convex-louvre configuration), the test results show that the sensible heat transfer performances are relatively independent of fin pitch. However, for type III slits, which feature the smallest distance between adjacent slits, a drop of heat transfer performance for N= 1 and Fp = 1.81 mm is observed. It is very likely that this phenomenon is related to the ‘non-recovery wake effect’ caused by the slit geometry. A correlation is proposed for the slit fin configuration; the mean deviations of the proposed heat transfer and friction correlation are 8.0 and 8.1 per cent respectively.
WangC. C.Recent progress on the air-side performance of fin-and-tube heat exchangers. Int. J. Heat Exchangers, 2000, 1, 49–76.
2.
McQuistonF. C.Correlation of heat, mass and momentum transport coefficients for plate-fin-tube heat transfer surfaces with staggered tubes. ASHRAE Trans., 1978, 84(1), 294–309.
3.
EckelsP. W.RabasT. J.Dehumidification: On the correlation of wet and dry transport process in plate finned-tube heat exchangers. Trans. ASME, J. Heat Transfer, 1987, 109, 575–582.
4.
WangC. C.HsiehY. C.LinY. T.Performance of plate finned tube heat exchangers under dehumidifyingconditions. Trans. ASME, J. Heat Transfer, 1997, 119, 109–117.
5.
WangC. C.LinY. T.LeeC. J.An airside correlation for plain fin-and-tube heat exchangers in wet conditions. Int. J. Heat Mass Transfer, 2000, 43, 1867–1870.
6.
MirthD. R.RamadhyaniS.Prediction of cooling-coils performance under condensing conditions. Int. J. Heat Fluid Flow, 1993, 14, 391–400.
7.
MirthD. R.RamadhyaniS.Correlations for predicting the air-side Nusselt numbers and friction factors in chilled-water cooling coils. Expl Heat Transfer, 1994, 7, 143–162.
8.
WangC. C.DuY. J.TaoW. H.Airside performances of herringbone fin-and-tube heat exchangers in wet conditions. Can. J. Chem. Engng, 1999, 77, 1225–1230.
9.
WangC. C.TaoW. H.DuY. J.Effect of waffle height on the heat transfer and friction characteristics of wavy fin-and-tube heat exchangers under dehumidification. Heat Transfer Engng, 2000, 21(5), 17–26.
10.
WangC. C.LinY. T.LeeC. J.Heat and momentum transfer for compact louvered fin-and-tube heat exchangers in wet conditions. Int. J. Heat Mass Transfer, 2000, 43, 3443–3452.
11.
HongK.WebbR. L.Performance of dehumidifying heat exchangers with and without hydrophilic coatings. Trans. ASME, J. Heat Transfer, 121, 1018–1026.
12.
WangC. C.ChangC. J.DuY. J.Airside performance of slit fin-and-tube heat exchangers in wet conditions. In Proceedings of the 34th National Heat Transfer Conference, Pittsburgh, Pennsylvania, 2000, paper 12092.
13.
ASHRAE Standard 41.2-1987 Standard Methods for Laboratory Air-Flow Measurement, 1987 (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta).
14.
ASHRAE Standard 41.1-1986 Standard Method for Temperature Measurement, 1986 (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta).
15.
ASHRAE Standard 33-78, 1978 Method of Testing Forced Circulation Air Cooling and Air Heating Coils, 1978 (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta).
16.
MoffatR. J.Describing the uncertainties in experimental results. Expl Thermal Fluid Sci., 1988, 1, 3–17.
17.
ThrelkeldJ. L.Thermal Environmental Engineering, 1970 (Prentice-Hall, New York).
18.
MyersR. J.The effect of dehumidification on the air-side heat transfer coefficient for a finned-tube coil. MSc thesis, University of Minnesota, Minneapolis, 1967.
19.
GnielinskiV.New equation for heat and mass transfer in turbulent pipe and channel flow. Int. Chem. Engng, 1976, 16, 359–368.
DuY. J.WangC. C.An experimental study of the airside performance of the superslit fin-and-tube heat exchangers. Int. J. Heat Mass Transfer, 2000, 43, 4475–4482.
22.
PauleyL. L.HodgsonJ. E.Flow visualization of convex louver fin arrays to determine maximum heat transfer conditions. Expl Thermal Fluid Sci., 1994, 9, 53–60.
23.
WangC. C.TsaiY. M.LuD. C.Comprehensive study of convex-louver and wavy fin-and-tube heat exchangers. Am. Inst. Aeronaut. Astronaut. J. Thermophys. Heat Transfer, 1998, 12, 423–430.
24.
SuzukiK.NishiharaA.HayashiT.SchuergerM. J.HayashiM.Heat transfer characteristics of a two-dimensional model of a parallel louver. Heat Transfer Jap. Res., 1990, 19, 654–669.
25.
XiG. N.HagiwaraY.SuzukiK.Flow instability and augmented heat transfer of fin arrays. J. Enhanced Heat Transfer, 1995, 2, 23–32.
26.
DejongN. C.JacobiA. M.An experimental study of flow and heat transfer in parallel-plate arrays: Local, row-by-row and surface average behavior. Int. J. Heat Mass Transfer, 1997, 40, 1365–1378.
27.
KafesjianP.PlankC. A.GerhardE. R.Liquid flow and gas phase mass transfer in wetted wall towers. Am. Inst. Chem. Engrs J., 1961, 7, 463–466.
