bloudup008
Mechanical
What is the most economical(operation cost) type of heating system for a green house application, ±180 kW?
Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Greenhouse heating
- Thread starter bloudup008
- Start date
- Status
.
Earth Air Heat Exchangers are commonly used. Check out this document: " ro a Internet search for (("Earth Air Heat Exchanger" OR "earth tube" OR "earth air tube") greenhouse india)
.
tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation
Earth Air Heat Exchangers are commonly used. Check out this document: " ro a Internet search for (("Earth Air Heat Exchanger" OR "earth tube" OR "earth air tube") greenhouse india)
.
tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation
This will depend on the climate at the location of the greenhouse, cost of fuel supplies, lighting requirements, temperature requirements, etc. Also you have restricted the answer to operational costs only so you can get some very capital intensive answers.
I perform a fair amount of energy audits on greenhouses. Greenhouses are designed to capture solar thermal energy directly. In the warm climate on the California Coast it is common for them to become too hot so ventilation controls are important. In cold areas anything that can be done to reduce night sky radiation of heat back to the atmosphere will reduce heating requirements. Photovoltaic solar energy would be useful only if the greenhouse had electric storage capability (batteries) or you could (electrically or thermally) heat water in an insulated tank and store that for cooler periods such as the nights or winter. Solar would only work if you had additional areas to locate the solar panels since you would not want to block the sunlight from the greenhouse itself.
A considerable amount of greenhouses have lighting fixtures which supply Photosynthetically Active Radiation (PAR) which provides the energy for the plant photosynthesis. When this occurs heating is usually not a problem since I have seen up to 680 watts of lighting for every 25 square feet of greenhouse area.
The most common forms of greenhouse heating that I see is gas fired (either direct infrared or convective through a boiler). Although this can be expensive the few number of days that is required in the main California greenhouse areas does not make the additional capital cost for more efficient systems cost effective.
I think the most cost effective measures would be those that reduce heat loss (or are able to control heat loss) through the greenhouse building envelope. I have not seen any of the earth tubes that tsgrue mentions but it sounds very interesting. I did see one greenhouse in Idaho that used geothermal hot water to heat the greenhouse.
I perform a fair amount of energy audits on greenhouses. Greenhouses are designed to capture solar thermal energy directly. In the warm climate on the California Coast it is common for them to become too hot so ventilation controls are important. In cold areas anything that can be done to reduce night sky radiation of heat back to the atmosphere will reduce heating requirements. Photovoltaic solar energy would be useful only if the greenhouse had electric storage capability (batteries) or you could (electrically or thermally) heat water in an insulated tank and store that for cooler periods such as the nights or winter. Solar would only work if you had additional areas to locate the solar panels since you would not want to block the sunlight from the greenhouse itself.
A considerable amount of greenhouses have lighting fixtures which supply Photosynthetically Active Radiation (PAR) which provides the energy for the plant photosynthesis. When this occurs heating is usually not a problem since I have seen up to 680 watts of lighting for every 25 square feet of greenhouse area.
The most common forms of greenhouse heating that I see is gas fired (either direct infrared or convective through a boiler). Although this can be expensive the few number of days that is required in the main California greenhouse areas does not make the additional capital cost for more efficient systems cost effective.
I think the most cost effective measures would be those that reduce heat loss (or are able to control heat loss) through the greenhouse building envelope. I have not seen any of the earth tubes that tsgrue mentions but it sounds very interesting. I did see one greenhouse in Idaho that used geothermal hot water to heat the greenhouse.
AbbyNormal
Mechanical
Usually a greenhouse only needs heat to melt the snow of the roof or to keep it warm at night.
If you are prone to snow I would use belted unit heaters and poly tubes. Have a damper to switch the heat high to melt snow, and low for at night.
Some places maybe geosource is a good application.
Can be sunny as hell, -25C outside and +25C inside when the sun is shining
Take the "V" out of HVAC and you are left with a HAC(k) job.
If you are prone to snow I would use belted unit heaters and poly tubes. Have a damper to switch the heat high to melt snow, and low for at night.
Some places maybe geosource is a good application.
Can be sunny as hell, -25C outside and +25C inside when the sun is shining
Take the "V" out of HVAC and you are left with a HAC(k) job.
AbbyNormal
Mechanical
pair of 400,000 Reznors with blowers
Take the "V" out of HVAC and you are left with a HAC(k) job.
Take the "V" out of HVAC and you are left with a HAC(k) job.
- Status
Similar threads
- Locked
- Question
- Locked
- Question
- Locked
- Question
