Effect of Dynamic Vents on the Thermal Comfort of a Passenger Car

Environment friendliness and energy efficiency are the mantra of today’s world in each and every sector of development. The automotive industry is also now switching to zero emission car concepts to be in congruence with this concept. During this transformation, however, consumer satisfaction should not be hampered. The consumer is satisfied if he feels comfortable using a given commodity. Comfort, being a physiological or psychological factor, is basically a subjective term. Thermal comfort is therefore also a subjective term, dependent on heat conduction, convection, radiation and evaporative heat loss. Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI/ ASHRAE Standard 55) [1]. The predicted mean vote (PVM) is the most recognized thermal comfort model whose seven point scale varies from –3 (cold) to +3 (hot). Zero is the ideal value, representing thermal neutrality, i.e. a neutral thermal sensation is achieved when the human body is in thermal equilibrium with the surroundings. Heat generated by a human body depends on the metabolism of the system. Each part of human body has a different metabolism rate. Because of the numerous differences between the physiological and psychological satisfaction of human beings it is very difficult to pinpoint a temperature that would provide the same level of thermal comfort to every passenger of a vehicle. The thermal comfort for the passenger of the car is maintained by the HVAC (Heating, Ventilation and Air-Conditioning) system. Therefore, the number of vents, air-flow temperature and velocity, cabin temperature and relative humidity are the main parameters that control the inner environment of a passenger car. The thermal comfort sensation is optimal when the relative humidity value is about 50 %. Humidity fluctuations play a minor role if the values are in the range of 30 % to 70 % [2]. Thermal comfort in the vehicle is achieved (i) by ensuring temperatures of 20 °C to 22 °C, as a result of air temperature, delimitation areas, humidity and air velocity in accordance with the activity level and clothing insulation of the occupants, (ii) by avoiding situations such as the occupants coming into contact with very cold or very hot surfaces, (iii) by avoiding air Effect of Dynamic Vents on the Thermal Comfort of a Passenger Car Singh, O.P. – Raut, R. – Biswas, M. – Singh, R. Om Prakash Singh1,* – Rohit Raut1 – Mrinmoy Biswas1 – Ramji Singh2 1 Indian Institute of Technology Mandi, School of Engineering, India 2 Aryabhata Knowledge University, India