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HỘI THẢO QUỐC TẾ ATiGB LẦN THỨ CHÍN - The 9 ATiGB 2024 29

3. RESULTS AND DISCUSSION 14 Ambient air humidity 70%
A. Simulation of the Thermal Loads Applied to 15 Cabin air humidity 40%
the Cabin
The input parameters used for calculation and
simulation were presented in Table I. The dimension
of the vehicle cabin was shown in Fig. 1. The results
of the simulation of the thermal loads applied to the
vehicle cabin were presented graphically in Fig. 2.
During the operation of the vehicle‘s air
conditioning system, the system's operating efficiency
depends greatly on the heat applied to the cabine. Fig.
1 showed that radiation heat had the greatest influence
with the value up to 2227.8 W. This proved that when
the vehicle worked in hot weather, radiation heat
exchange was very high, and today, most cars have
been equiped by insulated glass. The heat emitted Figure 1. Cabin geometry
from humans sitting in the car depended mainly on the
number of people, and had little impact on the heat
exchange process in the cabin. This heat value was up
to 317.08 W.
The thermal parameters such as heat exchanged
with the air, heat emitted from the engine, and heat
loss due to ventilation changed continuously during
the operation of the air conditioning system. In
particular, the heat loss due to ventilation was quite
large. This was the case of choosing the outside air
mode, and the heat loss could be up to -1666 W. This
heat increased over the heat exchange time, and
reached the nearly maximum value of -1634,19 W
after 720 seconds.
The heat exchanged with the air and the heat
emitted from the engine had a negligible effect on the Figure 2. Diagram of the heat change vz time
air condition system. These parameters gradually
increased over the heat exchange time. The heat B. The Cooling Capacity of the Vehicle Air
exchanged with the air reached the nearly maximum Conditioning System
value of 100.81 W and heat emitted from the engine The cooling capacity of the air conditioning system
reached the nearly maximum value of 37.5 W after was determined by (14). In order to achieve the
720 seconds. required capacity of the system, the operating
Table 1. Input parameters used efficiency of the air conditioning system must meet all
for calculation and simulation thermal loads applied to the cabin, and the temperature
No Parameter Value in the cabin must be reduced to the required
1 Driver weight 65 (kg) comfortable value in a short time period of about 10 -
2 Passenger weight 60 (kg) 12 minutes. Therefore the total heat applied to the
cabin must be determined at the maximum value in the
3 Driver height 1.65 (m) operation process of the air conditioning system. Then,
4 Passenger height 1.60 (m) the maximum values of the thermal loads parameters
5 Vehicle velocity 45 (km/h) and the cooling capacity were presented as in Table II.
6 Glass thickness 0.005 (m) Table 2. Thermal loads parameters
7 Body shell thickness 0.01 (m) and the cooling capacity of air conditioning sytem
8 heat transfer coefficient of the glass 1.05
o
(W/m. C) No Parameter Maximum Value
o
9 heat transfer coefficient of the body shell 0.2 (W/m. C)
1 Heat emitted from humans, Q hum 317.08 W
10 Engine speed 3000 RPM
11 Ambient temperature 35 ( C) 2 Radiation heat, Q rad 2227.8 W
o
12 Initial cabin temperature 65 ( C) 3 Heat exchanged with the air, Q amb 101.08 W
o
13 Required comfortable temperature 25 ( C) 4 Heat emitted from the engine, Q eng 37.95 W
o
ISBN: 978-604-80-9779-0