Optimal thermohydraulic performance of artifically roughened solar air heaters

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Solar Energy (Journal of Solar Energy Science and Engineering); (United States)

DOI:https://doi.org/10.1016/0038-092X(91)90039-Y· OSTI ID:5109254

Prasad, B N; Saini, J S ^[1]

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1. Univ. of Roorkee (India)

The heat transfer coefficient of solar air heaters can be increased by providing artificial roughness on the bottom of the absorber plate, leading to higher collection efficiency. Inclusion of artificial roughness, however, results in a higher friction factor and consequently a higher pumping power is required. Results show that both the Nusselt number and friction factor increase with increasing relative roughness height and decrease with increasing relative roughness pitch, but not in direct proportions. Optimization of the roughness and flow parameters (p/e, e/D, Re) to maximize heat transfer while keeping friction losses minimum was attempted. It has been found that a particular value of roughness Reynolds number (e{sup +} = e/D {radical}{ovr f/2Re}), always corresponds to optimum thermohydraulic conditions in the range of parameters investigated. On this basis design curves have been developed that give the optimal thermohydraulic performance combination of these parameters.

• OSTI ID: 5109254
• Journal Information: Solar Energy (Journal of Solar Energy Science and Engineering); (United States), Journal Name: Solar Energy (Journal of Solar Energy Science and Engineering); (United States) Vol. 47:2; ISSN SRENA; ISSN 0038-092X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140901* -- Solar Thermal Utilization-- Space Heating & Cooling
AIR HEATERS
DESIGN
EFFICIENCY
ENERGY CONSUMPTION
ENERGY TRANSFER
EQUATIONS
EQUIPMENT
FLAT PLATE COLLECTORS
FLOW RATE
FLUID FLOW
FLUID MECHANICS
FRICTION FACTOR
HEAT TRANSFER
HEATERS
HYDRAULICS
LAMINAR FLOW
MECHANICS
NUSSELT NUMBER
OPTIMIZATION
PARAMETRIC ANALYSIS
PERFORMANCE
PUMPING
ROUGHNESS
SOLAR ABSORBERS
SOLAR AIR HEATERS
SOLAR COLLECTORS
SOLAR EQUIPMENT
SURFACE PROPERTIES
THERMAL EFFICIENCY
THERMODYNAMICS
TRANSITION FLOW
TURBULENT FLOW