Articles
GREENHOUSES HEATING BY THE SIMULTANEOUS USE OF THERMAL SCREENS AND UNDERGROUND PIPES
This greenhouse was heated by means of underground pipes and helped with thermal screens.
The conditioning system studied in this paper consists of underground pipes laid horizontally which act as “air-ground” heat exchangers.
Ambient air inside the greenhouse under the thermal screens is forced through the pipes and subsequently expelled once more into the former.
The system exploits the thermal inertia of the soil whose temperature at a certain depth is virtually constant.
This system is complemented with the thermal screens effect.
The screens function are: to decrease the radiation-convection lost, to diminish the air volume that must be heated by the underground pipes system and to diminish the air volume – soil area ratio.
The greenhouse is simulated by joining together two systems, the first consisting of a one-dimensional dynamic model of the greenhouse with the thermal screen, the second of a two-dimensional model of the pipes.
In both cases only primary conditions and heat and mass transfer processes are considered.
The mathematical equations used for the simulation are presented.
With the aim of get comparative results of the system, the greenhouse was divided in two parts, one with heating system and the other one without heating.
The simulation and experimental results are presented.
This results show a good approach.
The results show, also, the saving energy of the system and a good thermal performance.