Air-conditioning and Cooling technology Page 25

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Plant slope

For a desired constant room temperature, the transmission heat increases linearly with sinking outside temperatures ts. In order to now cover the increasing heat loss, the supply air temperature t1 must also be raised linearly (not taking extraneous heat into account). The proportionality factor of such a heating curve is known as slope.

English translation of technical terms and sentences in the formula above:

Anlagensteilheit = Plant slope

Plant slope is thus dependent upon the necessary change in the supply air temperature t2 per K change in the outside temperature t3 and the necessary change in supply air temperature is, in turn, determined by transmission (insulation) and the specified air exchange rate.

1.4.3 Calculation formulae

Room air renewal

If the necessary outside air volume \/3 has been determined in m3/s for the ventilated room shown in Fig. 20, the heat output Q of the air heater, expressed in kJ/s = kW, necessary for heating the outside air at the temperature t3 to the supply air temperature t1, can be calculated from the following equation:

Fig. 20 Room air renewal

English translation of technical terms and sentences in Fig. 20:

= heat output
Zulufttemperatur = supply air temperature
Außenlufttemperatur = outside air temperature
Dichte der Luft = air density
Spez. Wärme der Luft = specific air heat

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