관경 변화에 따른 R-1234yf의 증발 압력강하에 관한 실험적 연구

국문 초록 (Abstract)

HFC계 냉매인 R-134a는 GWP가 높아 환경 문제를 일으키고 있으므로 이를 대체하여 열역학적 특성이 유사하고 GWP가 낮은 HFO계 냉매 R-1234yf를 연구하고자 한다. 그러나 R-1234yf에 대한 실험적 연구는 매우 부족한 실정이다. 따라서, 우리는 R-1234yf의 증발 압력강하 메커니즘을 명확하게 규명하기 위해 연구가 필요하다고 생각했다. 실험조건은 질량유속 200~500 kg/㎡s, 열유속 5~10 kW/㎡, 포화온도 5~15°C 및 관경 3.7~6.8 mm이다. 압력강하는 포화온도가 증가함에 따라 감소한다. 밀도 및 점도계수비가 각각 27, 15%씩 감소하기 때문이다. 또한, 압력강하는 열유속이 증가함에 따라 증가하는 경향이 있다. 이는 모든 관경에 대해 질량 유량이 클수록 압력강하가 커지며, 낮은 건도보다 높은 건도에서 압력강하가 증가한다는 것을 보여준다. 관경은 감소할수록 압력강하가 증가하였다. 내경 3.7~6.8 mm관 내 R-1234yf의 증발 압력강하를 타 상관식으로 예측한 값을 비교한 결과 각 평균오차 –15.3%, -21.3%로 좋은 일치를 보였다.

다국어 초록 (Multilingual Abstract)

The HFC refrigerant R-134a has a high GWP and causes environmental problems. Hence, we intend to replace it with the HFO refrigerant R-1234yf with similar thermodynamic properties and a low GWP. However, experimental studies on R-1234yf are very scarce. Therefore, research is needed to clearly elucidate the mechanism of evaporation pressure drop of R-1234yf. The experimental conditions for the present study were a mass flow rate of 200~500 kg/㎡s, a heat flux of 5~10 kW/㎡, a saturation temperature of 5~15°C, and a diameter of 3.7~6.8 mm. From the experiments, we observed that the pressure drop decreases as the saturation temperature increases. This is because the density and viscosity coefficient ratio decrease by 27 and 15%, respectively. The pressure drop also tends to increase with an increasing heat flux. This shows that for all pipe diameters, the greater the mass flow rate, the greater the pressure drop. The pressure drop also increases at higher vapor quality than at lower vapor quality. Moreover, as the pipe diameter decreased, the pressure drop increased. As a result of comparing the values predicted by other correlation formulas for the evaporation pressure drop of R-1234yf in pipes with inner diameter 3.7~6.8 mm, the average error was -15.3% and -21.3%, respectively, showing good agreement.

목차 (Table of Contents)

• 요약
• Abstract
• 1. 서론
• 2. 실험장치 및 데이터 정리
• 3. 실험 결과 및 고찰
• 4. 압력강하 상관식과 비교
• 5. 결론
• References

참고문헌 (Reference)

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