보조 외부 열교환기 및 사방밸브 적용을 통한 의류건조기의 히트펌프 성능개선 = Performance Improvement of a Clothes Dryer Heat Pump through the Application of an Auxiliary External Heat Exchanger and 4-Way Valve

국문 초록 (Abstract)

전통적인 벤트(vent, 열풍배기식 건조) 방식 의류 건조기는 단순한 건조과정을 통해 빠른 시간내에 직물을 건조시킬 수 있는 장점이 있으나, 이 방식은 습기와 함께 열풍을 기기외 부로 배출하여 환경에 부정적인 영향을 미치고 에너지 효율이 낮다는 단점이 있다.
최근 개발된 히트펌프 방식은 이러한 단점을 극복한다. 히트펌프 건조기는 냉매 사이클 을 이용해 열을 효율적으로 이동시키며, 벤트 방식에 비해 에너지 사용을 크게 줄이면서도 친환경적인 건조가 가능하다. 이 방식은 에너지를 절약하고 외부로 습기를 배출하지 않아, 가정용 의류 건조기 시장에서 점차 대체되고 있다.
가정용 의류 건조기 대비 상업용 건조기는 일반적으로 더 큰 처리 용량과 높은 사용 빈 도를 갖고 있으며, 대부분 벤트 방식을 사용한다. 하지만 이 방식은 환경 지속 가능성에 부 합하지 않으며, 글로벌 환경 지속 가능성 기준인 ESG(ESG, Environmental, Social, Governance))[13]에도 반하는 문제가 있다. 이에 상업용 환경에서도 히트펌프 방식의 도입 이 증가하고 있지만, 건조 시간을 단축시키는 추가적인 기술 개발이 필요하다.
본 연구에서는 히트펌프 의류 건조기의 기본 사이클에 외부 열교환기와 사방밸브를 도입 하여, 냉매 순환 방향의 전환을 통한 외부 열교환기의 기능 가변에 대한 영향도를 건조시 간 관점에서 실험적으로 고찰하였다.예열 건조 구간에서 외부 열교환기를 보조 증발기의 기능을 하게 함으로써, 외부계로의 추가 흡열을 통한 증발열량 및 응축열량 향상 효과가 확인되었다. 이로 인해 드럼 입구온 도 승온시간이 외부 열교환기를 구성하지 않은 기본 사이클 대비 약 40.1% 단축되었다.
항률 및 감률 건조 구간에서 외부 열교환기를 보조 응축기의 기능을 하게 함으로써, 외 부계로의 방열을 통해 압축기의 회전수를 높게 유지하면서, 토출 온도를 제한온도 이하로 보전할 수 있음이 실험에서 확인되었다. 또한, 과냉도 확보를 통해 증발기 입구 냉매의 건 도가 약 30% 감소하였고, 이로 인한 냉동효과 개선이 확인되었다.
응축기 출구 공기온도가 높은 상태에서 사방밸브를 절환 제어하는 것이 건조시간에 유리 한 것으로 확인되었다. 그러나, 외부계로의 흡열 과정에서 발생하는 응축압력의 상승으로 압축기의 부하가 증가하므로, 압축기의 허용전류를 고려한 사방밸브 절환 제어가 필요하다. 본 실험에 적용한 히트펌프 시스템과 압축기 사양을 고려하여 응축기 출구 공기온도가
65 °C 도달 시 사방밸브를 절환하는 제어를 채택하였다.
상기의 효과를 종합하여 전체 건조시간의 개선효과를 확인 시 기본 사이클 대비하여 외 부 열교환기 및 사방밸브를 적용한 사이클의 건조시간이 약 14% 단축되었다.
따라서, 본 연구에서는 히트펌프 의류 건조기에 사방밸브를 활용하여 한 개의 외부 열교 환기를 건조 구간에 맞게 기능 가변시켜 외부계와 흡열 및 방열과정을 통한 건조시간이 단 축이 가능함을 실험적으로 입증하였다.

목차 (Table of Contents)

• 제 1 장 서론 ······························································································ 1
• 1.1 연구배경 ················································································ 1
• 1.2 의류 건조기 이론 ···································································· 3
• 1.2.1 건조 방식의 기술적 차이점 ············································ 3
• 1.2.2 직물 건조 단계별 특성 ·················································· 4
• 제 2 장 선행연구 및 연구목적 ···································································· 14
• 2.1 선행연구 ·············································································· 14
• 2.2 연구목적 ·············································································· 17
• 제 3 장 실험장치 및 방법 ······································································ 24
• 3.1 실험장치 ·············································································· 24
• 3.1.1 실험장치 구성 ·························································· 24
• 3.1.2 건조부하 ································································· 25
• 3.2 실험방법 ·············································································· 25
• 제 4 장 실험결과 및 고찰 ······································································ 37
• 4.1 사방밸브 절환시점별 실험결과 ················································ 37
• 4.1 예열 건조구간 실험결과 ························································· 44
• 4.1.1 증발 열량 및 응축 열량 향상효과 ······························· 44
• 4.1.2 드럼 입구온도 승온시간 단축효과 ······························· 44
• 4.2 항률 및 감률 건조구간 실험결과 ············································· 52
• 4.2.1 냉매유량 향상효과 ···················································· 52
• 4.2.2 건도 및 냉동효과 개선 ·············································· 54
• 4.3 건조성능 영향 ······································································ 63
• 제 5 장 결론 ······························································································65
• 참고문헌 ·································································································· 67
• Abstract ·································································································· 70