F2010C044
The Human Thermal Comfort Evaluation Inside the Passenger Compartment
As many people spend several hours a day in cars, buses or trains, it is important to provide a good thermal environment, which gives comfort and optimizes performance for both drivers and passengers. Therefore, the most of the automotives manufactures have focused on the increasing of the habitable comfort by highly effective and efficient HVAC systems.
The interaction of convective, radiation and conduction heat exchange in a passenger's compartment is very complex. The varying radiation from the sun and the influence of inhomogeneous air temperature and air velocity from the vehicle's ventilation or air conditioning system creates a climate that may vary considerably in space and time. The efficiency of the HVAC system is evaluated by taking into account the equivalent temperature and the surface temperature of clothing of the passengers.
The thermal comfort sensation is assured by the factors that depend on the heat exchange between the human body and the ambient environment.
It is well known that one of the requirements to be fulfilled is that a person to be in thermal neutrality according to the comfort equation. This is described and evaluated by the following index: DTS (Dynamic Thermal Sensation), PMV (Predicted Mean Vote) and PPD (Predicted Percentage of Dissatisfied). The first index depends of the hypothalamus temperature and the mean skin temperature and PMV - PPD indices take into account the following six parameters: activity, clothing, air temperature, mean radiant temperature, air velocity and humidity (ISO 7730).
The level of thermal comfort is highly dependent on the local environment. Human beings respond differently to local heat transfer in different parts of their bodies. It is suggested for that reason that local results from manikins should be presented in new clothing independent comfort zone diagrams.
This paper shows the influence of the different parameters and situations on the thermal human comfort prediction of passengers' compartment starting from the body's energy balance based on Fiala's manikin (which provides all the thermo-physiological effects of the human body model) by THESEUS-FE software.
On the other hand, this simulation is likened to the temperature values which are measured in 12 different points of passenger compartment and are obtained on the experimental way;
Consequently, this paper will presents the different aspects of the global and local thermal comfort prediction, based on mathematical models from literature, as well as using simulated skin and cloth temperatures result to a quite simple-to-use method of assessing local thermal comfort at given boundary conditions, typical for a vehicle simulation. Considering not only surface-to-surface radiation and convection but also sun radiation, seat contact and evaporation the equivalent temperature can then be derived at each body element sector of a thermal manikin.
This abstract is supplemented by a PDF, which can be viewed here.
Poster presentation: Test, simulation and calculation methods of vehicles and components