Thermal-economic analysis of a heat pipe heat exchanger for energy recovery in air conditioning applications

Abstract

The computer simulation and working fluid selection of a heat pipe heat exchanger (HPHE) system appropriate for both heating and cooling modes in air conditioning applications are performed in this article. The studied heat pipes had a screened mesh wick and methanol as the working fluid. Various numbers of heat pipes and different values of return to the total outlet air mass flowrate ratio were considered. The heat transfer rate in HPHE was computed by the ε—NTU method by considering appropriate heat pipe thermal resistance. Because of its higher evaporation enthalpy and appropriate working limits, methanol was selected as the working fluid. Checking the heat transfer limits showed that the minimum heat transfer rate was well above the required heat transfer rate. Furthermore, the economic analysis of the HPHE was performed considering initial (investment) and operational costs as well as annual savings due to energy recovery for different numbers of heat pipes and various values of return air ratio. The results showed that there was a design point at which the savings of energy recovery was the maximum. The characteristics of this point at various values of return air ratio were determined and reported for the most economical HPHE design and for manufacturing purposes.

Keywords

heat pipe heat exchanger heat recovery economic analysis ε—NTU method

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References

Peterson

G. P.

, An introduction to heat pipes, modeling, testing, and application (New York: Wiley 1994).

Faghri

, Heat pipe science and technology (Washington, DC: Taylor and Francis 1995).

Dunn

Reay

D. A.

, Heat pipes (Oxford: Pergamon Press 1982).

Peretz

Bendescu

, ‘The influence of the heat pipe heat exchanger's geometry on its heat transfer effectiveness’ Heat Recovery Syst. CHP 3 (1983): 23–34.

Tan

J. O.

Liu

C. Y.

Wong

U. W.

, ‘Heat pipe heat exchanger optimization’ Heat Recovery Syst. CHP 11 (1991): 313–319.

Hagens

Ganzevles

F. L. A.

Van der Gled

C. W. M.

Grooten

M. H. M.

, ‘Air heat exchangers with long pipes: Experiments and predictions’ Appl. Therm. Eng. 27 (2007): 2426–2434.

Yau

Y. H.

, ‘Application of a heat pipe heat exchanger to dehumidification enhancement in HVAC system for tropical climates—a baseline performance characteristics study’ Int. J. Therm. Sci. 46 (2007): 164–171.

Noie-Baghban

S. H.

Majideian

G. R.

, ‘Waste heat recovery using heat pipe heat exchanger (HPHE) for surgery rooms in hospitals’ Appl. Therm. Eng. 20 (2000): 1271–1282.

Abd El-Baky

M. A.

Mohamed

M. M.

, ‘Heat pipe heat exchanger for heat recovery in air conditioning’ Appl. Therm. Eng. 27 (2007): 795–801.

10.

Soylemez

M. S.

, ‘On the thermoeconomical optimization of heat pipe heat exchanger HPHE for was heat recovery’ Energy Convers. Mgmt. 44 (2003): 2509–2517.

11.

Soylemez

M. S.

, ‘On the optimum heat exchanger sizing for waste heat recovery’ Energy Convers. Mgmt. 41 (2000): 1419–27.

12.

Tan

J. O.

Liu

C. Y.

, ‘Predicting the performance of a heat pipe heat exchanger using the effectiveness NTU method’ Int. J. Heat Fluid Flow 11 4 (1990): 376–379.

13.

Incorpera

F. P.

Dewith

D. P.

, Fundamental of heat and mass transfer (New York: John Wiley and Sons 1996).

14.

Mc Quiston

Tree

D. R.

, ‘Optimum space envelops of the finned tube heat transfer surface’ ASHRAE Trans. 78 11 (1972): 144.

15.

Engineering Science Data Unit (ESDU). High-fin Staggered tube banks: Heat transfer and pressure drop for turbulent single phase gas flow, ESDU Item 86022 (London: ESDU International Ltd. 1986).

16.

Kays

W. M.

London

A. L.

, Compact heat exchangers (New York: McGraw-Hill 1984).

17.

Huang

B. J.

Tsuei

J. T.

, ‘A method of analysis for heat pipe heat exchangers’ Int. J. Heat Mass Transf. 28 (1985): 553–562.