scholarly journals Heat Rejection and Energy Extraction within Solar Ponds

1982 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Energy Extraction ◽  
Heat Rejection ◽  
Solar Ponds

Effect of Thermal Buoyancy on the Recirculating Flow in a Solar Pond for Energy Extraction and Heat Rejection

1984 ◽  
Vol 106 (4) ◽  
pp. 428-437 ◽  
Author(s):  
C. K. Cha ◽  
Y. Jaluria
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Practical Interest ◽  
Temperature Fields ◽  
Energy Extraction ◽  
Heat Rejection ◽  
Solar Ponds ◽  
Thermal Buoyancy ◽  
Recirculating Flow ◽  
Solar Pond

An analytical and numerical study is carried out to determine the effect of buoyancy, resulting from temperature differences, on the recirculating flow arising in enclosed regions, such as the surface and storage layers of a salt-gradient solar pond, due to the discharge of fluid into it. The study investigates the time-dependent flow, considering an initially isothermal or thermally stratified fluid region, and the approach to the steady-state circumstance. Various flow configurations and boundary conditions, of particular relevance to energy extraction and heat rejection in solar ponds, are considered. The governing parameters, particularly the buoyancy parameter, are varied to determine the dependence of the flow field on these. Both laminar and turbulent flow are considered and numerical results are obtained for the velocity and temperature fields in the pond. Several interesting features are observed, particularly the strong effect of thermal buoyancy on the flow in the range of physical variables of practical interest and the effect of the flow on the growth and decay of a stable thermal stratification in the enclosed region. The effect of a periodic heat input into the region is studied. The study also considers relevant one-dimensional steady and transient analytical models for the thermal field and results are presented to indicate the range of validity of such simple models. The results obtained are also compared with earlier numerical and experimental studies of this flow circumstance and a fairly good agreement is observed. The relevance of the work to practical solar ponds is also outlined.

Theoretical Performance of a Solar Pond With Enhanced Ground Energy Storage

1996 ◽  
Vol 118 (2) ◽  
pp. 101-106 ◽  
Author(s):  
R. Prasad ◽  
D. P. Rao
Keyword(s):  
Energy Storage ◽  
Energy Extraction ◽  
Flat Bottom ◽  
Solar Ponds ◽  
Solar Pond ◽  
Salt Requirement ◽  
Extraction Pattern ◽  
Convective Layer ◽  
Theoretical Performance ◽  
Variable Energy

A method was proposed earlier by the authors for the enhancement of energy storage in the ground beneath solar ponds employing the trapezoidal-shaped trenches at the bottom of the pond. The theoretical performance of the solar pond with trapezoidal trenches is presented for constant and variable energy extraction patterns. The results indicate that the trenches could be effective in reducing the thickness of lower convective layer and hence the salt requirement of the pond. However, the effectiveness of the trenches seems to be dependent on the energy extraction pattern. For the constant extraction pattern of 63.9 W m−2, it is found that 36.5 percent reduction in the salt requirement can be achieved with 3-m deep trenches compared to the flat-bottom pond. For the variable extraction pattern, the reduction was only 21.5 percent.

Comparing Expanders for Direct Recovery of Exhaust Energy From a Low-Heat-Rejection Diesel

1987 ◽  
Vol 109 (4) ◽  
pp. 396-401 ◽  
Author(s):  
C. A. Amann
Keyword(s):  
Flow Characteristics ◽  
Constant Speed ◽  
Energy Extraction ◽  
Heat Rejection ◽  
Part Load ◽  
Internal Expansion ◽  
Positive Displacement ◽  
Exhaust Energy ◽  
A Performance

Part-load performance of a compound low-heat-rejection (LHR) engine is estimated at constant speed. The engine consists of an LHR diesel reciprocator geared to a supercharging compressor and an exhaust expander. Two classes of expander differing substantially in both flow characteristics and energy-extraction principles are ranked: aerodynamic (reaction turbine) and positive-displacement (internal expansion). To focus the comparison on differences in fundamental expander characteristics rather than differences in efficiency levels among specific samples of each type of expander, each is assigned an efficiency of 100 percent at its best-efficiency point. Although differences in fundamental characteristics between the expanders were sufficient to rank them on a performance basis, these differences were largely overshadowed by the magnitude of the indicated work developed in the reciprocator relative to the work developed by the expander.

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