00/00495 Some aspects concerning modelling the flow and heat transfer in horizontal mantle heat exchangers in solar water heaters

2000 ◽  
Vol 41 (1) ◽  
pp. 52
1997 ◽  
Vol 119 (3) ◽  
pp. 193-200 ◽  
Author(s):  
S. D. Dahl ◽  
J. H. Davidson

Determining the performance of indirect solar heating systems that use thermosyphon heat exchangers requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. In this paper, measured performance of a two-pass, tube-in-shell, double-wall heat exchanger is discussed in terms of modeling issues. Thermosyphon heat exchangers may operate in the developing, mixed convection regime where natural convection effects can significantly influence overall heat transfer and friction coefficients. Existing models which assume the thermal and hydraulic behaviors of thermosyphon heat exchangers are only functions of the thermosyphon and collector flow rates may not be suitable for all heat exchanger types. For example, the overall heat-transfer coefficient-area product for the two-pass, tube-in-shell heat exchanger is best expressed as a function of Reynolds, Grashof, and Prandtl numbers on the thermosyphon side of the heat exchanger. It is proposed that annual simulations of solar water heaters with thermosyphon heat exchangers use this type of relationship to characterize heat transfer in the heat exchanger.


Solar Energy ◽  
2009 ◽  
Vol 83 (3) ◽  
pp. 350-362 ◽  
Author(s):  
Y.C. Soo Too ◽  
G.L. Morrison ◽  
M. Behnia

Solar Energy ◽  
1999 ◽  
Vol 67 (1-3) ◽  
pp. 79-91 ◽  
Author(s):  
L.J. Shah ◽  
G.L. Morrison ◽  
M. Behnia

Author(s):  
Aaron P. Eicoff ◽  
Mohammad H. Naraghi

A model for the combined spectral radiative, conductive and convective heat transfer analysis of solar water heaters is presented. The radiation aspect of this model is based on the spectral distribution of the solar irradiance and spectrally selective properties of the system components. The convective equations that were used are based on well-established empirical models. The heat transfer characteristics of the solar water heater are determined by simultaneously solving a nonlinear system of energy balance equations for the various physical components using an iterative approach. The model is used to predict temperatures and heat fluxes for a typical flat-plate solar collector for various geometries and conditions i.e. flow rates, solar irradiances and spectral properties.


Solar Energy ◽  
2003 ◽  
Vol 74 (6) ◽  
pp. 441-445 ◽  
Author(s):  
J. Razavi ◽  
M.R. Riazi ◽  
M. Mahmoodi

Solar Energy ◽  
1999 ◽  
Vol 67 (1-3) ◽  
pp. 53-64 ◽  
Author(s):  
Graham L. Morrison ◽  
Gary Rosengarten ◽  
Masud Behnia

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