دانلود رایگان مقاله انگلیسی بررسی تجربی بر روی ویژگی های عملکرد مبدل حرارتی سرد برای خودرو ISG - اشپرینگر 2017

ABSTRACT

The ISG (Idle Stop and Go) system isvery useful in the automobile industry because it increases fuel consumption and reduces green house gas emissions. However, when the engine is on standby, the air-conditioning system does not work due to compressor inactivity, causing thermal discomfort to passengers. This study examines the thermal storage system, which is a cold storage heat exchanger integrated with a current evaporator. The experiments were conducted for an optimum cold storage heat exchanger design with various fin heights and densities, a number of stacking evaporator plates, refrigerant flow circuits inside the evaporator, and PCMs (Phase Change Materials) in the heat exchanger. The effects of coldness-release performance were examined with various ambient temperatures and air flow volume rates to the cold storage heat exchanger. The visualization of PCM’s freezing and melting was conducted with the cold storage heat exchanger. From the results, we found that the air discharge temperature of the air-conditioning system that was applied to the optimum cold storage heat exchanger was delayed around 540 seconds compared to the current air-conditioning system to reach 24 °C. Thus we can say that the cold storage heat exchanger integrated with an evaporator is an effective solution for ISG vehicles in maintaining thermal comfort in vehicle cabins during short engine stops.

4. CONCLUSION

When operating in ISG mode in a vehicle, since the compressor of an air-conditioning system stops, thermal comfort in cabin worsens. As an alternative, a thermal storage system with an evaporator-assembled cold storage heat exchanger was studied and the following conclusions were obtained.

Cold storage heat exchanger performance was optimized by changing refrigerant circuit, fin height and fin density. As a result of experimenting with various cold storage PCMs, the time for the temperature of discharging air to reach 24 °C from the supplying air temperature of 29 °C was around 310 ~ 360 seconds.

It was confirmed by visualization for the thermal storage and thawing of the thermal storage unit that PCM is icestored to solid over 10 minutes, and it can last more than around 2 minutes when releasing coldness.

Supplying air temperature and air flow volume rate has a significant influence on the thermal storage system, and it was found that coldness releasing performance dropped when temperature was higher and air flow volume rate was larger.

It took around 540 seconds for the temperature of discharing air to reach 24 °C for the air-conditioner with cold storage heat exchanger #2 and PCM A, and the temperature rise was lower by 4.8 °C at around 180 seconds in contrast to the current Base.

Therefore, the evaporator-assembled cold storage heat exchanger was optimized through the experiment; as a result of analyzing the influence on performance of airconditioning systems using the applied heat exchanger, the thermal storage system is considered to be very useful in maintaining occupant comfort while also increasing vehicle fuel efficiency during idle stop time or while waiting at a traffic light signal.