Room (complex)

File: Room Complex.doc

Last edition: 2003-03-20/MK

Author: Lars Halling

History: 96-03-01/HN First released version

96-10-04/MK Updated to Menta 1.20

97-09-01/MK Updated to Menta 3.0

98-12-16/MK New file namne.

2003-03-20/MK Updated to Menta 4.0

Description

Model of a room with a constant air flow entering the zone. The temperature in the room is controlled by changing the temperature of the supply air. The model is a first order model. The gain is calculated as function of the number of air changes per hour, the area of the room surfaces and the heat transfer coefficient of these surfaces. The time constant is in addition to the factors mentioned above also dependent of the heat capacity of the air in the room. In addition to the constants listed below, one should also note the influence of the parameter Tb. Tb denotes the temperature of the surroundings, i.e. the temperature of walls et.c. Since the temperature of the air in the room in general will change much faster than the temperature of the surroundings we have simplified the model by introducing this constant temperature, Tb, of the surroundings.

Inputs

(Real) Supply Temp, °C (Tin)

Outputs

(Real) Room Temp, °C (Troom)

Constants

(Real) vol = room volume (m3). Nominal value = 50 m3.

(Real) AW = area of room surfaces, i.e. walls, ceiling and floor (m2). Nominal value = 80 m2.

(Real) qair = supply air flow (m3/h). Nominal value = 265 (m3/h).

(Real) h = heat transfer coefficient for room surfaces (W/(K*m2)). Nominal value = 2.0 W/(K*m2).

(Real) cp = specific heat capacity for air = 1000 J/(kg*K).

(Real) rho = density of air (kg/m3) = 1.2 kg/m3, at P = 101315Pa and 20°C.
(1993 ASHRAE HANDBOOK, FUNDAMENTALS).

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