UNGLAZED SOLAR COLLECTORS FOR HEATING SWIMMING POOLS

Ziel

The demonstration of unglazed polypropylene collectors for solar heating of outdoor and indoor swimming pools in eight different sites in England.
Total water surface: 3 346 m2
Total solar surface: 1 704 m2.
All the pools except one, were monitored for at least two seasons. It was shown that unglazed collectors can heat swimming pools during the summer in England.
The pool covers were not easy to handle and seldom put on during the night.
In some pools no covers were put at all. The system efficiency per season varied between 50-20% in 1982. Equal hydraulic distribution through the panels was not solved satisfactorily which explains the variation in the system efficiency of the different installations. The solar fraction is the solar contribution to the total energy demand during the monitored period.
Merchant Taylor School's pool has no auxiliary heating. The system efficiency is therefore high. With a pool cover the variation of the temperature could be kept much smaller and higher solar fractions achieved in all the pools.
Wind speeds of 2 m/s on average were found in Warrior Square and Willesden Sport Center in 1982.
Due to warm summer in 1983 the system efficiency and the solar fraction were improved. Northbrook is a fine example how to tune the solar system for better performance results. The originally computed efficiency was never achieved because it assumed perfect conditions as to flow rate and controlling. The performance of solar heating systems at 4 indoor and 4 outdoor pools - all large installations for school or local authorities - was monitored over a two-year period, and found to save significant amounts of energy.
For the outdoor pools (21-24 C) the energy contribution was +- 300 Kwh/m2 of collector area per season. For the indoor pools, generally heated to higher temperatures (25-27 C) the energy saving was +- 200 Kwh/m2 of collector area during an average season.
Assuming the pools are heated by oil with a mean temperature of less than 25 C, giving a solar energy contribution of 280 Kwh/m2 annually, simple payback is estimated at 8.2 years (1985 costs).
A number of problems arose during commissioning of the individual systems. While the majority were minor, a few were quite significant:
HYDRAULIC DESIGN :
Flow distribution was uneven or inadequate through the collectors at several sites. This was due to a combination of the following factors;
1. incorrect flow rate through the solar circuit;
2. incorrect pipe layout or pipe sizing
3. too many collectors per bank.
Optimum flow rate range is 0.03 to 0.05 Kg/m2 sec (100-180 Kg/m2 h). Provided total flow rates are within recommended limits, up to 8 collectors per bank are recommended. If it is not possible to determine flow rate, a safety factor may be built-in by installing only 6 or 4 collectors/bank.
COLLECTOR DRAINBACK OR DRAINDOWN:
The solar heating systems are designed to ensure the collectors and connecting pipework may be fully drained to provide frost protection, a function which failed to work satisfactorily at several sites. It was concluded that all piping should be laid to adequate falls to permit complete draining.
Eight swimming pools are equipped with unglazed polypropylene (Robinson) absorbers.

Name and location Swimming pool type Water surface Absorber surface
Dragon School outdoor 275 m2 115.5m2
Oxford
Biggleswade outdoor 475 m2 288.0 m2
Bedford
Warrior square indoor 495 m2 194.4 m2
Southend-on-sea
Essex
Willesden Sports indoor 498 m2 295.2 m2
Centre, Willesden
Stanborough Park outdoor 770m2 336.0 m2
Grange Paddocks indoor 316 m2 230.4 m2
Bishops Stortford
Merchant Taylors outdoor 287 m2 144.0 m2
School, Northwood
Northbrook School indoor 220 m2 100.8 m2
Exeter

Total 3 346 m2 1 704.3 m2
The pool water is passed directly through the panels. In most cases an additional pump is used. The collectors are mounted on standardized metallic racks either on the ground or on surrounding buildings. Removable pool covers exist at some pools.

Programm/Programme

ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984

Thema/Themen

3.2 - SWIMMING POOLS

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

DEM - Demonstration contracts

Koordinator

Robinsons Developments Ltd

EU-Beitrag

Keine Daten

Adresse

Robinson House Winnall Industrial Estate
SO23 8LH Winchester
Vereinigtes Königreich

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