Abstract
A hybrid solar collector, in this study, means the flat plate solar collector that has a fin-and-tube heat exchanger combining with a heat pump system. This collector can get the thermal energy from the ambient air for heating the circulated water in the collector when solar radiation is not enough. Thus, this collector can supply thermal energy to evaporator of the heat pump using heated water. For a foundation design of this collector, the numerical analysis was conducted for confirming the heat gain of water by the ambient air according to the length and the installation angle of fins in the fin-and-tube heat exchanger of solar collector. As a result, much of heat gain of water was obtained on the higher fin length with 30o of installation angle, but the pressure drop of air side increased adversely with heat transfer rate. Thus an area goodness factor considering both heat transfer enhancement and pressure drop of air side was also investigated. As a result, 50 mm of the fin length with 0o of installation angle has a good heat transfer enhancement than that of the other installation conditions compare with increment of pressure drop. However, mostly, higher heat transfer rate was obtained when the area goodness factor was low. So, it is needed to be considered whether the condition, maximum value of area goodness factor satisfying the heat transfer rate, can be expected or not.
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- \( \dot{Q}: \) :
-
Heat transfer rate [W]
- \( \dot{m}: \) :
-
Mass flow rate [kg/s]
- T ::
-
Temperature [℃]
- U ::
-
Overall heat transfer coefficient \( \left[ {\text{W}/{\text{m}}^{2} {\text{K}}} \right] \)
- \( C_{p} : \) :
-
Specific heat of heating medium [kJ/kgK]
- \( \text{F:} \) :
-
Correction factor [–]
- \( \Delta T_{lm,CF} : \) :
-
Logarithmic mean temperature difference on counter flow [℃]
- \( A_{o} : \) :
-
Air-side total surface area \( \left[ {{\text{m}}^{\text{2}} } \right] \)
- \( A_{i} : \) :
-
Tube inner surface area \( \left[ {{\text{m}}^{\text{2}} } \right] \)
- \( A_{m} : \) :
-
Tube mean surface area \( \left[ {{\text{m}}^{\text{2}} } \right] \)
- \( A_{t} : \) :
-
Tube outer surface area \( \left[ {{\text{m}}^{\text{2}} } \right] \)
- \( A_{f} : \) :
-
Fin surface area \( \left[ {{\text{m}}^{\text{2}} } \right] \)
- \( D_{h} : \) :
-
Hydraulic diameter \( \left[ {\text{m}} \right] \)
- h ::
-
Heat transfer coefficient [\( \text{W}/{\text{m}}^{2} {\text{K}} \)]
- \( \Delta x\text{:} \) :
-
Tube thickness \( \left[ {\text{m}} \right] \)
- k ::
-
Thermal conductivity \( \left[ {\text{W}/\text{m}{\text{K}}} \right] \)
- \( d_{t} : \) :
-
Tube diameter \( \left[ {\text{m}} \right] \)
- V ::
-
Velocity \( \left[ {{\text{m}}/{\text{s}}} \right] \)
- \( \Delta {\text{P:}} \) :
-
Pressure drop \( \left[ {\text{Pa}} \right] \)
- \( {\text{F}}_{\text{L}} : \) :
-
Fin length [mm]
- \( {\alpha :} \) :
-
Installation angle of fin [o]
- Re ::
-
Reynolds number [–]
- Pr ::
-
Prandtl number [–]
- \( j: \) :
-
Colburn j factor [–]
- \( f_{p} : \) :
-
Petukhov friction factor [–]
- \( f: \) :
-
Friction factor [–]
- \( \eta \text{:} \) :
-
Surface efficiency [–]
- \( \eta_{f} : \) :
-
Fin efficiency [–]
- Ρ ::
-
Density \( \left[ {{{\text{kg}} \mathord{\left/ {\vphantom {{\text{kg}} {{\text{m}}^{3} }}} \right. \kern-0pt} {{\text{m}}^{3} }}} \right] \)
- w ::
-
Of water
- air ::
-
Of air
- avg ::
-
Of average
- i ::
-
Of inlet
- o::
-
Of outlet
References
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Choi, H.W., Rokhman, F., Lyu, N.J., Son, C.H., Yoon, J.I., Choi, K.H.: Numerical study on the optimum structure of air channel for heat gain of liquid from ambient air in hybrid solar collector. In: Proceedings of the KSES 2015 Autumn Annual Conference, p. 24 (2015)
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Acknowledgments
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20153030081190)
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Choi, H.U., Fatkhur, R., Kim, Y.B., Son, C.H., Yoon, J.I., Choi, K.H. (2017). A Numerical Analysis on Heat Transfer Between the Air and the Liquid in a Hybrid Solar Collector. In: Duy, V., Dao, T., Kim, S., Tien, N., Zelinka, I. (eds) AETA 2016: Recent Advances in Electrical Engineering and Related Sciences. AETA 2016. Lecture Notes in Electrical Engineering, vol 415. Springer, Cham. https://doi.org/10.1007/978-3-319-50904-4_17
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DOI: https://doi.org/10.1007/978-3-319-50904-4_17
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