Как выбрать гостиницу для кошек
14 декабря, 2021
To model the absorption chiller we are going to use the operation curves of the chiller given by the manufacturer. Thanks to these curves and depending on the inlet temperature of the generator, we will be able to determine the frigorific power of the chiller, a generator power and cooling power.
3.3. The cooling tower
To model the cooling tower, we considered a heat exchanger. The first fluid (1: the water), circulates through the exchanger, while the second fluid (2: the air), blows around and against the first flow. We chose to use the efficiency method and the formula is [8]:
with, ДТ^-Tjl-Tzl, (m ■* Cp)mln = nrin(™a * C* ій£ * Cj, 1 — е[-в»а-ві |
1 — C * e1 |
(ill* Cp) |
<*,сии |
= T. ‘ ^ …… ‘ " ‘ ^ ‘ T;: — T;: = "T.. ‘ ‘ T.: — T.; [8]
3.4. The Building
Here we present a simplified model of our classrooms. To do this we will consider a single area building and its main features are:
Length = 13m |
Glass: Simple glazing (S = 25m2) |
Students = 105 |
Width = 13m |
Wall: reinforced concrete (thickness = 16 cm) |
Lighting: 22 neon lights of 58W |
Height = 3m |
Infiltration air flight= 1 vol/h |
Occupation : de 8h00 a 18h00 |
[9]
[10]
We have now all equations needed to determine temperatures and powers throughout the day.
Our model needs to operate climatic data (sunshine and outside temperature). We chose those from the 2nd of June 2008. These data were derived from measurements made on our experimental platform by a weather station. Next, we must specify the time of occupation of the day: 10 AM to 12 PM and 1 PM to 5 PM. Then we have to set the initials temperatures inside the tow tanks (T_hot_tank = 66°C and T_cold_tank=20°C) as our installation on this day.
Tout_captor
Tout_arai
T_cold_tauk —
Toutside —
occupation
Fig. 5 et 6: Evolution des temperatures et des puissances des principaux composants
We can see the evolutions of temperatures and powers on fig. 5 and 6. We notice that at 8 AM, the solar collectors start to produce hot water and the hot tank warms gradually. Students arrive at 10 AM (occupation = 1) and then leave at 12 PM. They come back at 1 PM and leave at 5 PM. The air temperature in the building increases with the arrival of students to reach its peak (30°C) 30 minutes later.
We see that the absorption chiller starts at 11 AM, and that the powers have been slowly declining throughout its operation (5 hours).
We can notice that the outlet temperature of the solar collectors does not exceed 90°C and the temperature of the hot tank reaches its peak at 11 AM and down gradually to 65°C at 4:15 PM, when the absorption chiller stops. Meanwhile the cold tank has reached its minimum value (about 8°C) at around 1 PM and the minimum outlet temperature of the evaporator is 6°C.