Influencing assessment of different heating modes on thermal comfort in electric vehicle cabin

Electric vehicle(EV)is more environmental-friendly than gasoline vehicle because the main power is not petrol.For the heating system,the waste heat generated by engines is recycled to heat the cabin of gasoline ones,while the EV need extra electric energy consumption for heating the cabin which decreases the driving range.Personal comfort system(PCS)has been reported that it is an alternative technique to improve occupant thermal comfort and indirectly save building heating energy.This study aims to investigate the occupants’thermal sensation under four heating modes in the EV cabin in winter,including no heating,only PCS,only air conditioning,and both air conditioning and PCS.The field survey is conducted in a parked EV with 12 subjects.Three thermal comfort indexes(PMV,SET^(*),and operative temperature Top)are used and assessed for their applicability in the thermal environment of the EV.Results show that the thermal environment in the cabin is non-uniform and dynamic with the air conditioning mode,while the PCS mode just slightly affects the temperature differences inside.Meanwhile,the subjects’thermal sensations cannot maintain neutral or warmer under the PCS mode only.The results of PMV are lower than the subjects’actual thermal sensation votes(TSV),while the results of SET^(*)and Top show significant linear relationships with the TSV for the correlation coefficients above 0.80.Compare to the air conditioning mode,the neutral SET^(*)and neutral Top are decreased by 2.7℃ and 1.6℃ under the mode with PCS and air conditioning,respectively.The findings indicate that PCS not only has a positive effect on improving the cabin environment and occupant’s thermal sensation but also has the potential to lower the setting temperature of air conditioner of EVs in winter.

Thermal Comfort Analysis of Personalized Conditioning System and Performance Assessment with Different Radiant Cooling Systems

The radiant systems consume less energy and provide better thermal comfort as compared to the conventional system,but the main drawback of radiant technology is inability to cater the latent load and condensation.This problem has engaged researchers to push their emphasis on Personalized Conditioning System(PCS).It forms a micro-climate region near the occupant.This study is aimed at PCS combined with a radiant conditioning system,which evaluates the performance of the PCS and compares it with different radiant cooling systems.A radiant cubicle was used to investigate the performance of the PCS for both heating&cooling modes.For heating mode,the Standard Effective Temperature(SET)was calculated with the help of thermal comfort surveys which were in a range of 23.4℃ to 27.3℃.For cooling mode,four different cases compared the performance of the system which are:Conventional Air Conditioning System(CACS),Radiant Cooled Ceiling System(RCCS),Personalized Radiant Conditioning System(PRCS),and both PRCS-RCCS coupled.It was observed that PRCS alone reaches the thermal comfort criteria with low energy consumption.The energy-saving of RCCS-PRCS was achieved 38%when compared with CACS.It can be concluded that PRCS is a new step in the field of thermal comfort.