한국산학기술학회논문지 (Journal of the Korea Academia-Industrial cooperation Society)

  • 제20권1호
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  • Pages.21-27
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  • 2019
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  • 1975-4701(pISSN)
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  • 2288-4688(eISSN)
한국산학기술학회 (The Korea Academia-Industrial cooperation Society)
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소형 제빙기에 사용되는 R-404A 대체 R-448A, R-449A의 Drop-in Test에 대한 연구

A Study on the Drop-in Tests of a Small Ice Maker Using R-404A Replacements R-448A and R-449A

  • 투고 : 2018.09.28
  • 심사 : 2019.01.04
  • 발행 : 2019.01.31
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초록

그간 소형 제빙기에는 R-404A가 사용되어 왔으나 지구 온난화와 관련하여 대체 냉매 적용이 시급한 실정이다. 본 연구에서는 제빙기에 적용되어 온 R-404A를 대체할 R-448A와 R-449A에 대하여 drop-in test를 수행하였다. 시험은 외기 온도와 증발판에 공급되는 물 온도를 변화시키며 수행되었다. 실험 결과 R-404A의 일 평균 제빙량은 R-448A보다는 5.3%, R-449A보다는 4.2% 크게 나타났다. 이는 R-404A의 기체 밀도가 커서 냉매 순환량이 증가하기 때문으로 판단된다. 한편 R-448A와 R-449A의 제빙량을 비교하면 외기온도나 믈 온도가 낮아 제빙량이 많으면 R-448A가, 외기 온도나 물 온도가 높으면 R-449A가 우수한 성능을 보인다. 일 평균 소비 전력량은 R-448A나 R-449A보다 R-404A에서 대략 10% 크게 나타났다. 한편 성적계수의 경우 R-448A와 R-449A는 거의 동일하고 R-404A의 값보다는 3.0% 크게 나타났다. 현재 R-448A, R-449A의 증발, 응축 열전달에 대한 데이터가 부족한 실정으로 향후 이 부분에 대한 기초 연구가 필요할 것으로 판단된다.

R-404A, which is used widely in small-scale ice makers, is scheduled to be phased out because of its high global warming potential. In this study, drop-in tests were conducted using R-448A and R-449A, which replace R-404A, to modify the outdoor air and supply water temperatures. The results showed that the daily ice production rate of R-404A was 5.3% higher than that of R-448A and 4.2% higher than that of R-449A. This was attributed to the larger vapor density of R-404A, which resulted in a larger mass flow rate in the system. Between R-448A and R-449A, R-448A yielded a larger amount of ice at low air and water temperatures, whereas R-449A yielded a larger amount of ice at high air and water temperatures. The daily power consumption of R-404A was approximately 10% larger than those of R-448A and R-449A. The resulting COPs of R-448A and R-449A was similar, only 3.0% larger than that of R-404A. The literature survey showed that the condensation or evaporation data of R-448A or R-449A are very limited, and research on this issue is recommended.

키워드

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Fig. 1. Photo of an unitary ice maker

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Fig. 2. Refrigeration cycle of an unitary ice maker

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Fig. 3. Photo of an evaporator plate

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Fig. 4. Refrigeration cycles of the ice maker for R-404A, R-448A and R-449A

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Fig. 5. Daily ice production for different outdoor/water temperatures

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Fig. 6. Daily power consumption for different outdoor/water temperatures

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Fig. 7. COP for different outdoor/water temperatures

Table 1. Properties of R-404A, R-448A, R-449A

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Table 2. Test conditions of the ice maker

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Table 3. Specification of major components

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Table 4. Optimum refrigerant charge and expansion valve opening for different outdoor/water temperatures

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Table 5. Test results at 21°C outdoor and 10°C water temperature

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