Abstract Introducing solar energy into the gas turbine of Combined Cycle systems (CC) offers significant advantages over other solar power plant concepts. A promising way to introduce solar power is solar preheating of the compressor discharge air before it enters the combustor of the gas turbine using a receiver built consisting of several metallic tubes. The main challenge during the design of such a receiver is the low solar flux capability caused by the limited convective heat transfer. To ensure a sufficient efficiency, the receiver is usually located in a cavity. The heat losses by conduction through the (insulated) cavity walls can be reduced by increased insulation thickness. Heat losses by radiation and convection to ambient depend strongly on the aperture area, receiver inclination and the receiver temperature. The receiver temperatures can be reduced by increasing the cavity si ze, as the flux distribution gets more homogenous and the overall flux density is reduced. Following heat losses by radiation and convection to ambient are reduced. On the other hand additional costs for the cavity walls have to be considered. The paper deals with the comparison of two different strategies to increase the receiver efficiency of a cavity receiver used to heat the compressed air of a 4.7 MWel turbine from 330 °C up to 800 °C, with a mass flow of 15.9 kg/s at 10 barabs. The influence on the levelized cost of energy (LCOE) of different receiver sizes and one design option (transparent covering of aperture) for reducing the convections losses were analyzed and compared. The thermal and hydraulic layout was done for a thermal heat of 8.4MWth and 250 mbar pressure drop using thermal finite element (FE) models considering the local heat flux distribution, heat transfer to working fluid, radiation exchange between components and ambient as well as conduction and convection losses of the cavity. As the convective losses play a significant role, CFD models were used to evaluate the convective heat losses.
[1]
R. Y. Ma.
Wind effects on convective heat loss from a cavity receiver for a parabolic concentrating solar collector
,
1993
.
[2]
Ralf Uhlig,et al.
Development of a Broadband Antireflection Coated Transparent Silica Window for a Solar-Hybrid Microturbine System
,
2009
.
[3]
U. Leibfried,et al.
Convective Heat Loss from Upward and Downward-Facing Cavity Solar Receivers: Measurements and Calculations
,
1995
.
[4]
L. L. Eyler.
Predictions of convective losses from a solar cavity receiver
,
1979
.
[5]
Stefano Giuliano,et al.
Upscaling of solar-hybrid gas turbine cogeneration units - USHYNE (Phase 1)
,
2009
.
[6]
Ralf Uhlig,et al.
Development of a tube receiver for a solar-hybrid microturbine system
,
2008
.
[7]
Jinjia Wei,et al.
Thermal performance simulation of a solar cavity receiver under windy conditions
,
2011
.
[8]
R. K. McMordie.
Convection heat loss from a cavity receiver
,
1984
.
[9]
F. A. Blake,et al.
One MWth solar cavity steam generator solar test program
,
1977
.
[10]
Reiner Buck,et al.
Analysis Of Solar Thermal Power Plants With Thermal Energy Storage And Solar-Hybrid Operation Strategy
,
2011
.
[11]
Y. C. Wu,et al.
Solar Thermal Power Systems Advanced Solar Thermal Technology Project: Solar receiver performance in the temperature range of 300 to 1300/sup 0/C
,
1978
.
[12]
C. F. Hess,et al.
Experimental Investigation of Natural Convection Losses From Open Cavities
,
1984
.
[13]
A. M. Clausing,et al.
An analysis of convective losses from cavity solar central receivers
,
1981
.
[14]
John Pye,et al.
Numerical Investigation of Natural Convection Loss From Cavity Receivers in Solar Dish Applications
,
2011
.
[15]
A. M. Clausing,et al.
Natural Convection From Isothermal Cubical Cavities With a Variety of Side-Facing Apertures
,
1987
.