Preparatory experiments on seasonal storage in earth of excess heat from greenhouse
Abstract
An earth heat accumulator, directly beneath an experimental greenhouse, with possibilities for collecting excess solar heat by pumps and utilization of low temperature heat was investigated. Heat exchange with the accumulator is made by a system of buried polyethylene pipes. The heat accumulator was loaded by excess solar heat from the greenhouse, using heat pumps, during two summer months. A theoretical model for the heat flow in the accumulator was used to study the heat balance in the accumulator and its interaction with surrounding soil and greenhouse. The heat flow through the soil surface is utilized by the greenhouse giving a higher root zone temperature and a higher air temperature. It is suggested that a heat accumulator should be placed deeper beneath the soil surface. Its extension in depth should be larger, (about 10 to 15 m) in the specific boulder clay investigated. It is concluded that the method which uses buried horizontal pipes is not usable, and a technique for vertical pipe systems with high heat transfer must be investigated.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- December 1980
- Bibcode:
- 1980STIN...8231780A
- Keywords:
-
- Energy Conversion;
- Greenhouses;
- Heat Pumps;
- Heat Storage;
- Heat Transfer;
- Pipes (Tubes);
- Polyethylenes;
- Energy Storage;
- Polymers;
- Solar Heating;
- Underground Storage;
- Energy Production and Conversion