PCM을 혼입한 모르타르의 열적 성능 및 경제성 평가에 관한 연구

Abstract

현재, 전 세계는 인류활동으로 인한 에너지 고갈과 이산화탄소(CO2)를 주로 한 온실가스(GreenHouse Grass,GHG)에 따른 지구온난화 방지에 최우선의 노력을 기울이고 있다1). 따라서, 에너지 저감 및 이산화탄소 (CO2)배출 저감 대책은 국가는 물론 국제적 차원에서 매우 중요한 과제이다. 이에 따라, 기후변화 협약과 더불어 에너지 절약을 통한 온실가스 감축은 세계적 추세로 자리매김하고 있으며 건축물은 전체 온실가스 배출량의 35%를 차지하기 때문에 건축물에서의 에너지 절약은 전체 이산화탄소 감축에 지대한 영향을 미친다2-3). 한편, 최근 국내에서는 주택문화 및 생활 환경 변화에 따라 실내 환경에 대한 쾌적성 향상에 대한 요구가 더욱 증가되고 있다. 따라서, 건물의 에너지 절약과 실내 환경의 쾌적성을 유지하는 융합기술 개발이 요구되는 시점이며 이러한 기술은 크게 냉·난방과 단열기술로 나뉠수 있다. 한국의 주택은 전통적 좌식구조로서 온수순환 시스템을 통한 온돌바닥을 이용해 실내벽의 표면온도를 높여 재실자의 복사발열량을 줄여 주는 난방방식이다. 복사난방의 쾌적감을 높이기 위해서는 실내의 난방열을 일정하게 공급하여 온돌바닥과 실내공기의 온도차를 낮게 해야 하며, 냉방의 경우도 그 반대로 실내의 일정한 공기온도를 제어하지 못할 경우 그 불쾌감은 크게 높아진다. 따라서, 난방기와 냉방기의 과다운전으로 인한 에너지 문제가 크게 우려되는 방식이라 할 수 있다4). 이에, 잠열을 이용한 축열 방식으로 Phase Change Materials(이하, PCM) 을 이용한 융합기술의 적용은 실내 냉·난방기에 의한 열적 변화를 흡수하여 축열 기능을 수행함으로서 매우 효과적인 에너지 저감 및 CO2 저감 효과가 기대되는 기술이다5-8). 본 연구에서는 잠열 및 온도조절 기능을 하는 혁신적인 온도 조절 물질인 PCM9)을 시멘트 모르타르에 혼입하여 습식 축열재로서 바닥 적용을 고려하였다. 따라서, PCM의 우수한 잠열 성능을 통해 냉·난방 설비 시스템 작동 정지 후 peak 부하의 일부를 off-peak 부하로 이동시키는 형태10-11)로서 장시간 그 열을 유지하고 실내 쾌적온도를 가깝게 유지시킴에 따라 에너지 절약 및 그에 따른 CO2 저감 효과를 기대하였다.12-13). 또한, 실험을 통해 시공성, 단열성, 실내 쾌적성, 에너지 저감 및 그에 따른 CO2저감 효과 등을 동시에 만족하는 습식 축열재로서의 이용기술에 대한 방안을 제시하고자 하였으며 Fourier 의 열전도 기본식을 통한 관련 식을 이용하여 이를 평가하고 실험값에 의한 경제성을 분석함을 목적으로 하였다. 또한, 본 연구를 통해 PCM모르타르 상용화를 위한 기초적 자료를 마련하고자 한다.

1) Series1. 의 실험을 통해 PCM을 혼입한 모르타르가 OPC와 기타 단열재와 비교해 잠열 및 단열 성능이 우수하게 나타남을 확인하였다.

2) PCM용융점 23°C, 28°C 적용에 따른 냉·온 축열 구간 온도범위를 판단하고 Series2. 의 실험결과로 실내 쾌적온도(23˚C∼31˚C)에 효과적 온도유지를 위한 용융점이 31°C 인 것을 알 수 있었다.

3) Series1과 Series2의 실험을 통해 PCM모르타르(３０％）가 OPC와 비교시 냉·난방 평균을 기준으로 잠열 시간은 약 90분 이상, 약 10°C 정도의 온도차이를 나타내는 것을 확인 하였으며 혼입량에 따라 성능이 증대되는 것을 확인하였다.

4) 따라서, OPC와 비교시 상대적으로 우수한 PCM 모르타르의 냉·온 축열성능을 이용하여 실내 냉·난방기 On-Off 조절에 의한 약 30% 이상의 에너지 저감 효과와 그에 따른 CO2 저감 효과를 확인 하였다.

5) 실험에서 도출해낸 결과값과 Fourier의 열법칙을 이용해 PCM 혼입량별 열 전달 식을 제안하였으며 이를 통해 PCM혼입량별 모르타르의 열 전달량을 예측할 수 있었다.

6) 따라서, 본 논문에서 제시한 PCM모르타르 열 전달량 식은 PCM 혼입량별 모르타르의 열 효율 및 성능을 예측하기 위한 유용한 기초적 자료가 될 것이라 판단된다.

7) 본 논문의 결과를 근거로 PCM모르타르 적용시 냉·난방기 사용에 따른 경제성을 평가한 결과, 기존 바닥 모르타르에 비해 약 20%이상의 경제성을 나타냄을 알 수 있었다 . 8) PCM 모르타르의 실제 적용을 위한 추후 연구가 필요할 것으로 사료된다.| At present the whole world is concentrating the effort of the highest priority on the prevention of energy exhaustion and global warming attendant on GreenHouse Gas(GHG) which mainly has CO₂resulting from human activity(1).ThereforemeasuresforthedecreaseofenergyandCO₂emission are a very important problem in a global as well as national point of view. At this point the reduction of GreenHouse Gas through energy saving with climatic change agreement is taking the proper place as an international current and the energy saving of building has a considerable effect on the whole CO₂reduction because building accounts for 35% of the whole GreenHouse Gas emission. On the other hand, recently in Korea request for the improvement of comfort with indoor environment attendant upon the change of house culture and life environment is increasing more and more. So, development for the technique fusing the energy saving of building and the comfort of indoor environment is requested at this point of time. This technique is divided into air conditioning and insulation technique largely. The Korean house as a traditional sitting type is a heating system to reduce the radiant heat value of a person in the room by raising the surface temperature of indoor wall using the heated floor with a hot-water circulation system. To raise the comfort of radiation heating, we have to lower the temperature gap of heated floor and indoor air by supplying indoor heating at a fixed rate. Likewise, in the case of air conditioning, if we are not to control indoor air temperature fixedly the other way, the unpleasant feeling is raised remarkably. For that reason, from a point of view of the energy problem due to the excessive operation of a heater and air-conditioner, these systems are of grave concern. So,the application off using technique touse Phase Change Materials(hereinafter, PCM) by the heat storage way using latent heat is a technique to expect the effect of very efficient decrease for energy and CO2 because of performing regenerative function absor bing the thermal change byan indoor air-conditioner and heater. matching pace with this current of the times, considered building application of mixing mortar with PCM appropriately as floor and plastering mortar and evaluated measures for the efficient decrease of energy and CO₂through experiment. It also composed the expression of heat transmission and temperature gradient through experiment value examined them. In this study, the application of floor and inner wall was taken into consideration as wet heat storage material by mixing cement mortar with PCM(9), innovative material to perform the function of latent heat and temperature control. Therefore through the excellent latent heat efficiency of PCM, after stopping the operation of air conditioning and heating equipment system, by keeping the heat for a long time in a form to shift apart of peak loadt ooff-peak load andmaintaining temperature close to indoor comfort, we expected the effect of energy saving and the reduction of CO₂attendant upon it. Also through the experiment we tried to present the plan for the utilization technique as we the at storage material to satisfy at the sametime constructability, an adiabatic function, indoor comfort, and the effect of energysaving and the reduction of CO₂attendant upon it, etc. and aimed at evaluating this using related expression through Fourier’s heat conduction basic expression.

1) We ascertained that mortar mixing with PCM in comparison with OPC and the other heat insulators in the efficiency of latent heat and insulation changed excellently, through the experiment.

2) As a result of conclusion for the temperature extent of cold and warm thermal storage section pursuant to application of 23°C, 28°C and 31°C for the melting point of PCM, we found that the melting point to keep indoor comfort temperature(23˚C∼31˚C) effectively is 31°C.

3) Through the experiment of Series1 and Series2 mortar with PCM in comparison with OPC, on the average of air conditioning and heating we ascertained that the latent heat time is over 90 minutes approximately and the difference of temperature is around 10℃.

4) Therefore, we could ascertain the effect of energy saving of over 30% and CO2 reduction pursuant to it by controlling on-off indoor air conditioners and heaters using the cold and warm thermal storage efficiency of mortar with PCM which is better in comparison with OPC.

5) We presented heat conduction expressions according to the content of PCM using result value drawn from experiment and Fourier’s heat law and could estimate the quantity of heat conduction for mortar by the content of PCM.

6) We think after this, more studies are needed to improve the real constructability, when mixing mortar with PCM.; At present the whole world is concentrating the effort of the highest priority on the prevention of energy exhaustion and global warming attendant on GreenHouse Gas(GHG) which mainly has CO₂resulting from human activity(1).ThereforemeasuresforthedecreaseofenergyandCO₂emission are a very important problem in a global as well as national point of view. At this point the reduction of GreenHouse Gas through energy saving with climatic change agreement is taking the proper place as an international current and the energy saving of building has a considerable effect on the whole CO₂reduction because building accounts for 35% of the whole GreenHouse Gas emission. On the other hand, recently in Korea request for the improvement of comfort with indoor environment attendant upon the change of house culture and life environment is increasing more and more. So, development for the technique fusing the energy saving of building and the comfort of indoor environment is requested at this point of time. This technique is divided into air conditioning and insulation technique largely. The Korean house as a traditional sitting type is a heating system to reduce the radiant heat value of a person in the room by raising the surface temperature of indoor wall using the heated floor with a hot-water circulation system. To raise the comfort of radiation heating, we have to lower the temperature gap of heated floor and indoor air by supplying indoor heating at a fixed rate. Likewise, in the case of air conditioning, if we are not to control indoor air temperature fixedly the other way, the unpleasant feeling is raised remarkably. For that reason, from a point of view of the energy problem due to the excessive operation of a heater and air-conditioner, these systems are of grave concern. So,the application off using technique touse Phase Change Materials(hereinafter, PCM) by the heat storage way using latent heat is a technique to expect the effect of very efficient decrease for energy and CO2 because of performing regenerative function absor bing the thermal change byan indoor air-conditioner and heater. matching pace with this current of the times, considered building application of mixing mortar with PCM appropriately as floor and plastering mortar and evaluated measures for the efficient decrease of energy and CO₂through experiment. It also composed the expression of heat transmission and temperature gradient through experiment value examined them. In this study, the application of floor and inner wall was taken into consideration as wet heat storage material by mixing cement mortar with PCM(9), innovative material to perform the function of latent heat and temperature control. Therefore through the excellent latent heat efficiency of PCM, after stopping the operation of air conditioning and heating equipment system, by keeping the heat for a long time in a form to shift apart of peak loadt ooff-peak load andmaintaining temperature close to indoor comfort, we expected the effect of energy saving and the reduction of CO₂attendant upon it. Also through the experiment we tried to present the plan for the utilization technique as we the at storage material to satisfy at the sametime constructability, an adiabatic function, indoor comfort, and the effect of energysaving and the reduction of CO₂attendant upon it, etc. and aimed at evaluating this using related expression through Fourier’s heat conduction basic expression.

1) We ascertained that mortar mixing with PCM in comparison with OPC and the other heat insulators in the efficiency of latent heat and insulation changed excellently, through the experiment.

2) As a result of conclusion for the temperature extent of cold and warm thermal storage section pursuant to application of 23°C, 28°C and 31°C for the melting point of PCM, we found that the melting point to keep indoor comfort temperature(23˚C∼31˚C) effectively is 31°C.

3) Through the experiment of Series1 and Series2 mortar with PCM in comparison with OPC, on the average of air conditioning and heating we ascertained that the latent heat time is over 90 minutes approximately and the difference of temperature is around 10℃.

4) Therefore, we could ascertain the effect of energy saving of over 30% and CO2 reduction pursuant to it by controlling on-off indoor air conditioners and heaters using the cold and warm thermal storage efficiency of mortar with PCM which is better in comparison with OPC.

5) We presented heat conduction expressions according to the content of PCM using result value drawn from experiment and Fourier’s heat law and could estimate the quantity of heat conduction for mortar by the content of PCM.

6) We think after this, more studies are needed to improve the real constructability, when mixing mortar with PCM.