# Solar-Enhanced Air-Cooled Heat Exchangers for Geothermal Power Plants

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## Abstract

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## 1. Introduction

## 2. Analysis

_{a}, increases the air enthalpy manifested in a temperature rise as

_{s}is the sunroof (panel) area, substituting for which leads to

_{p}and the air flow rate is given by $\dot{m}=\rho \pi DlU$, with l being the tower inlet opening height, D the sunroof diameter, D

_{b}the tower base diameter, ρ the air density, β the thermal expansion coefficient, H is the tower height and g is the gravitational acceleration.

_{a}= Nq. If the tubes are widely spaced, then q is the same as that given by a single tube in cross flow not disturbed by adjacent objects. With denser tube bundles, however, this is not the case. One can still define a per-tube heat transfer rate, but that will not be the same as the heat transfer from a single tube in cross flow. Combining the above equation with Equation (1), and substituting for the air-mass flow rate given by the continuity equation, one gets

_{r}being the tube’s outer (foam or fin) diameter divided by that of the bare tube. For a bare tube bundle, D

_{r}= 1. Moreover, the temperature difference $\Delta {T}_{sa}$ is the difference between the ambient air and average tube surface; the latter is very close to the average cycle fluid temperature or the condensation temperature. As such, this $\Delta {T}_{sa}$ can be thought of as approach.

## 3. Results

_{r}value of 1.75. Different sunroof diameters, ranging from D = 195 m to D = 475 m were examined. The whole 3D system was simulated using ANSYS and the numerical results and 1D theoretical prediction were cross-validated. Figure 3 shows a comparison between the new design offered here and that of Zou et al. [6,7,8], as summarized in [5].

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## 4. Conclusions

## Author Contributions

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) The SENDDCT concept investigated by Zou [5] and (

**b**) Schematic view of half of the tower (due to symmetry).

**Figure 2.**Close-up of an aluminium foam sample attached to a model condenser tube where the cells’ structures induce a tortuous flow path.

**Figure 3.**Heat transfer from the current design versus that of [5] for an identical tower size and height.

**Figure 4.**Heat transfer versus height for the current design with the tower details being the same as those of [5] except for H.

**Figure 5.**Required tower height for given sunroof diameters; other tower geometrical constraints are as those of [5].

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## Share and Cite

**MDPI and ACS Style**

Hooman, K.; Huang, X.; Jiang, F.
Solar-Enhanced Air-Cooled Heat Exchangers for Geothermal Power Plants. *Energies* **2017**, *10*, 1676.
https://doi.org/10.3390/en10101676

**AMA Style**

Hooman K, Huang X, Jiang F.
Solar-Enhanced Air-Cooled Heat Exchangers for Geothermal Power Plants. *Energies*. 2017; 10(10):1676.
https://doi.org/10.3390/en10101676

**Chicago/Turabian Style**

Hooman, Kamel, Xiaoxue Huang, and Fangming Jiang.
2017. "Solar-Enhanced Air-Cooled Heat Exchangers for Geothermal Power Plants" *Energies* 10, no. 10: 1676.
https://doi.org/10.3390/en10101676