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less humid, better crop

Innovative dehumidifying Demid unit saves energy, fight Botrytis

The Demid unit has been designed to specifically address the issues of humidity along side energy savings in the growing environment. Conventional heating systems are based around pipe heating and boilers and with the aid of roof ventilation; the humid air is driven out of the glasshouse. The Demid, with the aid of fans, circulates the air with closed roof ventilation. As a result less heat is required to maintain the environment as the prescribed level.

Developer Moshe Maroko from Agam Energy Systems was present at the OFA show with the unit. On the left his US distributor Zev Ilovitz from Resource Systems

Condensation builds up on the inner surface of the canopy, particularly at night time, due to the cold outside temperature and warmer internal temperature. This layer of water increases the speed at which the warm air from the inside can transfer to the outside and get wasted. The Demid reduces the amount of moisture in the air 24 hours a day (to a pre-set level), reducing the heat transfer through the glass and reducing the need to ventilate off excess humidity.

Botrytis spores become more prevalent when excessive humidity prevails. Poor air circulation, cold spots with in the growing area and high humidity all add to the risk of damaging the crop. Expensive chemical applications or extensive heat/ventilation programs have been the only solution.

Within the design of the Demid, there is a unique system where the humidity that is drawn into the unit becomes a source of energy or Latent Heat. As the moisture passes through a chemical brine solution, an exothermic reaction takes place which not only dries the air but heats it as well. One other by product is that the Botrytis spores are significantly reduced as they pass through the unit.

The product is gaining increased use throughout Europe on a variety of crops where humidity directly affects the crop. Latest tests in Sweden, in a standard Venlo glasshouse measuring 12,000sqm are very positive.

The unit requires a standard single phase supply (13a) and typically a 1” hot water supply from your pipe heating system. Tests showed that when the unit was in use, the optimum pipe temperature required was 74 deg C. During the trial, with no override, the unit could hold the relative humidity 20% lower than normal (normal being natural roof ventilation and pipe rail heat).

Measured energy consumption for the period was 60% lower in the test area. The period was during December and January 2012/2013.

For more information:
In the UK:
NP Structures (e-mail)

General information:

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