EML4930L7

EML4930L7 - Sustainable Energy Science and Engineering...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
S ustainable E nergy S cience and E ngineering C enter Flat Plate Collectors - Domestic Heating
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
S ustainable E nergy S cience and E ngineering C enter Simplified Collector Performance Model Prediction of the thermal output of various solar collectors: The quantity of thermal energy produced by any solar collector can be described by the energy balance equation where = rate of thermal energy output = rate of optical energy absorbed by receiver = rate of thermal energy lost from receiver. Ý Q out = Ý Q opt Ý Q loss Ý Q out Ý Q opt Ý Q loss Source: Solar energy Fundamentals and Design, William B. Stine & Raymond W. Harrigan, John Wiley & Sons, 1985
Background image of page 2
S ustainable E nergy S cience and E ngineering C enter Energy Losses E n e r g y Solar Insolation Tracking Reflection Focusing Transmittance Absorptance Convection Radiation Component Performance Fluid Transport Storage Power generation System integration Resource assessment Optical losses Thermal losses Component definition Subsystem definition System design
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
S ustainable E nergy S cience and E ngineering C enter System Performance U s e f u l E n r g y P o d c Operating Temperature C lle t b y m Power generation subsystem Combined system
Background image of page 4
S ustainable E nergy S cience and E ngineering C enter Optical Energy Absorbed by the Receiver Ý Q opt = A a ρ s , m τ g α r RSI a A a = specular reflectance of concentrating mirror, if any (1.0 for non- concentrating flat-plate collector) s , m = transmittance of any glass envelope covering the receiver (e.g. glass cover plate in a flat-plate collector) A a = aperture area of the collector S = receiver shading factor (fraction of collector aperture not shadowed by the receiver; 1.0 for a flat-plate collector) R = receiver intercept factor (fraction of reflected beam intercepted by receiver; 1.0 for a flat-plate collector) r = absorbance of the receiver I a = isolation (irradiance) incident on collector aperture (W/m 2 ) S, R, r , s,m and g are constants (in a more detailed model, the dependence of the angle of the incident insolation can be considered) dependent only on the materials used and the structure accuracy of the collector - they can be lumped into a single constant term η opt , the optical efficiency of the collector. For a flat-plate collector utilizing no reflectors, S, R and are set equal to 1.0.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
S ustainable E nergy S cience and E ngineering C enter Thermal Energy Lost from the Receiver Ý Q loss = A r U l T r T a ( ) A r = averaged receiver temperature ( o C) T r = surface area of the receiver (m 2 ) = ambient temperature ( o C) T a U l = overall heat loss coefficient (W/m 2 o C) T r = T out + T in 2 T out is the temperature in degrees C of the fluid leaving the collector while T in is the temperature of the fluid entering the collector. The heat loss coefficient U l is not a simple constant but instead may vary as heat-loss mechanisms change with temperature. For example as the temperature increases, radiant heat loss from the receiver increases.
Background image of page 6
S ustainable E nergy S cience and E ngineering C enter Ý Q out = A a η opt I a A r U l T r T a ( ) col
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 32

EML4930L7 - Sustainable Energy Science and Engineering...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online