Simple model and control strategy of earth-to-air heat exchangers
The worldwide energy situation forces industrialized countries to reduce their energy consumption, especially in the building sector, which makes up a high proportion of the total consumption. Techniques such as earth-to-air heat exchangers must therefore be developed and managed to meet this challenge. Yet earth-to-air heat exchangers provide better performance when linked to efficient control strategies.
Simulation of greenhouse microclimate produced by earth tube heat exchangers
Abstract 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 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. Two models simulating respectively the greenhouse and the underground pipes were modified and integrated so as to simulate the operation of the system. The heat and mass balance equations that constitute the resulting model are given. With the aim of finding the optimal characteristics of the system from the technico-economic point of view, this model was used to compute the heating of a typical greenhouse in the region (Humid Pampa zone, Argentina). The results obtained for different temperature requirements are given, together with the temperature gradients of the air inside the greenhouse on a typical day in winter, both with and without the conditioning system. Finally a comparison was made between the cost of running the system and a conventional one.
Simulation of simultaneous heat and moisture transfer in soils heated by buried pipes
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