Air-conditioning and Cooling technology Page 28

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Room air dehumidification

Drier supply air is directed into a room in order to extract excess moisture content x (g/s). Decisive factors are, on the one hand, the moisture difference between the desired room air moisture x1 and the supply air moisture x2, and on the other hand, the supply air volume V in m3/s. With a given difference x1 - x2 , the required air volume will be:

2. Model plant for technical service exercises

An experimental plant for the training of service technicians has been developed and constructed for the project partner from Meran. This model plant contains all the components of a complete air-conditioning plant, including a refrigerating set and a test room. The control was realised with a direct digital control, so that the area of control technology as an enhancement to electrical engineering (see MODULE V) could also be demonstrated and practised.

Description of the plant:

An actual room will be air-conditioned with this plant in order to achieve realistic conditions. The plant has been designed as a complete air-conditioning plant, and constructed in such a way that the processes in the plant are visible at all times. This means that all construction elements of the air-conditioning plant have been provided with a Plexiglas pane in front. Due to the limited spatial conditions, especially in classrooms, it seemed sensible to construct the complete air-conditioning plant at a 1:2 scale, instead of with standard sized components, in order to achieve smaller dimensions. The mounting was designed in such a way that parts of the plant could be covered by plates, allowing all partial functions, from the ventilating plant to the complete air-conditioning plant, to be explained step by step. In extreme cases all of the construction elements can be hidden by plates (see Fig. 22). Control is realised by means of a DDC. Thereby, up to eight prepared control elements of the individual procedures can be tried out.

The air-conditioning plant was constructed as follows:

Modular type with view window and pre-heater, filter, heat recovery, re-heater, cooler, humidifier (steam), fans for supply and exhaust air, mounted completely on a movable housing with a writing platform. The plant is constructed in such a way that a modular set-up, from the simple ventilation plant to the complete air-conditioning unit, is possible without a great deal of rebuilding. In addition, the individual components are constructed in a reduced scale. The maximum dimensions of the functional units are: circa: 30 x 30 x 30 cm, WRG: 30 x 30 x 50 cm. Because we are dealing here with a training air-conditioning plant, the design of the plant allows for a maximum capacity of 5 kW. All components are co-ordinated to this capacity.

In detail these are:

1 x pre-heater of sheet metal parts, powder coated with Plexiglas sheets on both sides, and with a quick opening mechanism.
Measurements: 30 x 30 x 30 cm
Capacity: 5 kW through electric heating bars - directed with a frequency converter for continuous capacity control
Voltage: 400V/16A

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