Environmental Engineering Reference
In-Depth Information
Acknowledgement
The author would like to thank Dr. Darwish Al Qubaisi for his continued support and
encouragement throughout this project.
Conclusion
The research operation of the test plant, conducted jointly between ENAA and WED,
ended successfully at the end of October 1985, as scheduled, giving many useful results that
are summarized below.
(1) System Reliability
The reliability of the automated continuous operation of the test plant for its first year of
operation has been successfully demonstrated. However, the plant has suffered from pump
trouble, etc. associated with plants of the same type in the early stage of development.
The plant's heat collecting subsystem, the heat accumulator subsystem and evaporator
subsystem have also proved to have no particular problems:
•
Corrosion of the heat collectors and heat accumulators was prevented by the use of
corrosion prevention chemical additive;
•
Scaling in the evaporator was prevented by using a scale inhibitor which maintained
a good evaporator performance throughout the first year without any need for an acid
cleaning;
•
Experimental results showed that there was no problem with the vacuum in the
evacuated glass tube collectors, despite early worries that the vacuum might
deteriorate if the collectors were left at no load (drained condition) without operation
under conditions of high solar radiation typical of the Middle East. The collector
joints were found to pose no problems in the first year of operation.
The above results have led to estimating the life expectancy of the solar collectors,
accumulators and evaporator at 20 years. The reliability of the plant has been further
demonstrated during its succeeding years of operation.
(2) Response to varying weather condition
Weather conditions, including solar radiation, ambient temperature, seawater temperature
and humidity varies widely according to the time of day and season. For example, the solar
radiation on a horizontal surface varied from 2,150 kcal/m
2
day to 7,080 kcal/m
2
and the daily
average temperature varied between 16.7
o
C and 38.0
o
C for 1985 in Abu Dhabi.
Despite such wide fluctuations, the results of the simulation program call for the
evaporator of the test plant to be shutdown only 13 times a year for lack of thermal charge in
the accumulator. Based on the simulation results also, the plant's annual operating time is
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