GREENHOUSE HEATING

GROUNDTHERM

Greenhouse system

The heating of the greenhouses is one of the most important factors in achieving a successful cultivation. Some plants require warm temperatures all year round, so it is essential to eliminate any heat loss and ensure temperature stability.

The heating system is used to keep the greenhouse temperature at a tolerable level when the outside temperature is low, which occurs during the winter months, or when the environment cannot meet the plants' needs for heat. The methods used to heat the greenhouse vary according to the needs of the producer, the location of the greenhouse, etc. However, each heating system must meet certain criteria such as :

Due to the better output of GROUNDTHERM system compared to ordinary systems, it can operate with lower water temperatures and therefore it can be well combined with modern energy saving systems, such as heat pumps, solar panels, geothermy etc. The hot water circulates inside Groundtherm pipes pipes, which were successfully tested on heating.

These pipes are produced by a special raw material, polypropylene Random in black color and they are very resistant to corrosion, to acidic soil environment, to fertilizers and to pesticides. Groundtherm pipes profil resembles a “Radiator” and has about twice the efficiency of the usual smooth pipe of polypropylene (diagram.1). The pipes are available in a nominal 25mm diameter and have nominal operating pressure 1,5 Bar at the usual heating temperature of greenhouses (50°C). They are accompanied by ta full range of fittings made from the same material.

Greenhouse heating study

The following data are required for the elaboration of the study:

Calculation example

A Groundtherm heating system will be installed in a greenhouse, on the ground between the rows of plants and the dimensions will be determined as follows.

DATA

Diagram 1.

Diagram 2.

HEAT OUTPUT PER CALCULATIONS

HEAT OUTPUT PER m OF PIPE
ΔΤ between average hot water temperature and room temperature 47.5 ° C -10 ° C = 37.5 ° C. From diagram 1 a pipe output of 50 W / m2 is obtained.
PIPE REQUIRED
Required energy W / m2: pipe output W / m = total pipe length in m / m2200 W / m2: 50 W / m = 4 m / m2.
Pipe length m/m2 x total surface m2 = total pipe length m. 4 m/m2 x 1000 m2 = 4000m.
AVERAGE DISTANCE OF PIPES
Total surface / total length 1000 m2: 4000 m = 0.25 m.
TOTAL WATER SUPPLY PER HOUR
Total required energy / (ΔT coefficient of transformation 200000 W / 5 ° C x 1.163 = 34394 L / h.
REQUIRED WATER SUPPLY IN EACH LOOP/h
Total supply x loop length / total length 34,394lt/hx80m/4000m=688lt/h.
TOTAL LOSS OF PRESSURE (from diagram 2)
For water supply 688lt/h diagram 2 gives loss of pressure 50mm WS/m that means that the total loss of pressure per loop is x loop length 50 mmWs / m x 80 m = 4000 Ws = 4mWs=0.4 Bar.