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An experimental method is proposed for evaluating the airtightness of a vehicle cabin and the ventilation effects of three components of the vehicle ventilation system. The measurement results are used to derive a theoretical equation to predict the total air infiltration rate of the cabin as a function of the pressure difference between the cabin interior and exterior, respectively. The validity of the predictive equation is demonstrated by means of fan pressurization experiments performed with the vehicle air-conditioning system set in the fresh air mode. It is shown that the prediction results for the total ventilation rate deviate from the experimental results by less than 10%. The infiltration ventilation effect of natural diffusion in the vehicle cabin is measured using the CO2 tracer gas method. The air exchange rate (ACH) of the cabin is found to be 0.816 in the recirculation air mode and 3.554 in the fresh air mode. [ABSTRACT FROM AUTHOR]

This study investigated the spray cooling heat transfer performance of Al2O3-water nanofluid given four different subcooling degrees (0 °C, 10 °C, 20 °C, and 30 °C). The results showed that the subcooled nanofluids were ranked in order of a reducing spray cooling heat transfer performance as follows: 20 °C, 10 °C, 0 °C, and 30 °C. On average, the heat transfer coefficient obtained using the nanofluid with 20 °C subcooling was around 8.3%, 8.6%, and 15.6% higher than that obtained with 10 °C, 0 °C, and 30 °C subcooling, respectively. However, the heat transfer performance decreased with an increasing spray operating time. The scanning electron microscopy observations showed that the reduction in the heat transfer coefficient was the result of a gradual increase in the thickness of the nano-adsorption layer on the heated surface as the spray operating time increased. [ABSTRACT FROM AUTHOR]

An experimental investigation is performed into the two-phase spray cooling heat transfer performance of Al2O3-water nanofluid given three different nanoparticle concentrations (0, 0.001 and 0.05 vol%) and three different spray operating times (10, 20 and 30 hours). The results show that for an Al2O3 concentration of 0 vol% (i.e., pure DI water), the spray operating time has a negligible effect on the heat transfer performance. However, for Al2O3 concentrations of 0.001 and 0.05 vol%, the heat transfer coefficient decreases with an increasing spray operating time. For the nanofluid with 0 vol% Al2O3, the spray operating time has only a small effect on the surface hydrophilicity. However, for the nanofluids with nanoparticle concentrations of 0.001 and 0.05 vol%, respectively, the surface hydrophilicity increases with an increasing spray operating time. Furthermore, the surface hydrophilicity also increases with an increasing nanoparticle concentration for a given spray operating time. The energy dispersive X-ray spectroscopy (EDS) results reveal the presence of a nanoparticle layer on the sprayed surfaces with a higher heat flux. The thickness of the deposited layer increases with an increasing spray operating time, and leads to a lower heat transfer performance and a higher surface hydrophilicity as a result. [ABSTRACT FROM AUTHOR]

This study investigates the air leakage ventilation phenomenon in a passenger car and examines its effects on the concentration of carbon dioxide in the cabin. A theoretical general equation ( Q AL = { [ A car (v car 2) m 1 ] 2 + [ A fan (v fan 2) m 2 ] 2 } 1 / 2 ) is proposed for predicting the air leakage ventilation rate. The validity of the equation is demonstrated by means of real car on-road experiments. The results show that when the car is at rest, the effect of the fan-supplied air speed on the air leakage ventilation rate is more apparent. However, for a moving vehicle, the contribution of the fan-supplied air speed to the cabin indoor air quality reduces, while that of the car speed increases. Applying a curve-fitting technique to the experimental data, it is shown that parameters Acar , m 1, Afan and m 2 in the proposed theoretical equation have values of 1. 15 × 10 - 4 , 0.725, 1. 6 × 10 - 3 and 0.315, respectively, for the present experimental car (a Mitsubishi Galant). In general, the results obtained in this study suggest that a fractional fresh air ventilation mode should be employed to guarantee the ASHRAE standard for the minimum fresh air requirement of 2.5 l/s per individual at low driving speeds. [ABSTRACT FROM AUTHOR]

Electric vehicles (EVs) generally use an electric heating system to provide heat. However, the heating system consumes a large amount of energy, and therefore reduces the mileage of the vehicle. The energy consumption can be reduced by replacing the electric heating system with a heat pump air conditioning system. Such systems achieve an effective heating of the vehicle interior, but do not provide a defog or dehumidification function. Consequently, the inside surface of the windshield tends to fog in cold weather; leading to poor driver visibility and an impaired road safety. Accordingly, the present study proposes a novel high-efficiency heating, ventilation and air conditioning (HVAC) system with both heating and defog/dehumidification functions for electric vehicles. The effectiveness of the proposed system is investigated experimentally using a simulated cabin placed in a temperature and humidity-controlled test chamber. The experimental results confirm that the HVAC system achieves the required cooling, heating and defog/dehumidification functions and meets the corresponding standards. Moreover, the application of HVAC in EVs could lead to significant electrical power saving effect. [ABSTRACT FROM AUTHOR]