• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.1
• /
• pp.77-85
• /
• 2007

One of the most common approaches to achieve better thermal comfort with the radiant floor heating system is supply water temperature control, which is that supply water temperature is varied with outdoor air temperature. But the application of this control method was not easy, because there has been no way to determine the supply water temperature. So in this study, a comprehensive, yet simple calculation method to find out the required supply water temperature is suggested by combining the building heat loss equation and the heat emission model of hydronic radiant floor heating system for single zone. And then using this calculation method, the multizone control method is suggested and confirmed through the thermal simulation. It is shown that indoor air temperature is stably maintained around the set point.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.112.2-112.2
• /
• 2011

PVT(Photovoltaic Thermal) 모듈은 태양광과 태양열 에너지를 동시 이용이 가능한 모듈로서 태양광전지(PV, Photovoltaic)모듈에 열교환기를 접합한 형태로 전기에너지뿐만 아니라 열에너지를 동시에 생산할 수 있는 시스템이다. 기존 PV 모듈은 일사량이 많으면 전력 생산량이 증가하는 동시에 PV모듈의 온도가 상승함에 따라 발전 효율이 감소하는 문제점이 있으며 일반적으로 $25^{\circ}C$이상 조건에서 모듈 온도가 $10^{\circ}C$ 증가할수록 발전효율의 약 4~5% 정도 감소하는 것으로 보고되고 있다. PVT 모듈은 기존 태양광모듈에 열교환기를 접합하여 냉각함으로써 PV모듈의 온도를 낮추어 발전효율을 증가시키는 동시에 부가적으로 발생하는 온수를 직접이용하거나 다양한 계통의 보조 열원으로 이용할 수 있는 장점이 있다. 본 연구에서는 수치해석기법(CFD)을 활용하여 PV모듈 냉각 및 온수 발생을 위한 열교환기를 설계하였으며 다양한 형상의 열교환기에 대해 유동해석을 수행하여 최적의 열흡수효율을 갖는 열교환기의 형상을 설계하였다. 또한 최적 설계된 PVT 모듈을 제작하여 실제 태양과 유사한 광원을 갖는 인공태양조건에서의 실내 실험을 통해 PVT 모듈의 성능을 검증하였으며 또한 실제 노상에 설치하여 ASHRAE 93-77의 실험기준과 ECN의 PVT 집열기 성능측정 가이드라인에 따라 옥외 시험평가를 하여 PVT 모듈의 성능 검증을 하였다. 최적 설계된 PVT모듈에 대한 성능평가 결과 기존 PV 모듈보다 발전효율이 약 15%(기존 발전효율 대비) 향상된 결과를 확인하였다.

• Plant Journal
• /
• v.10 no.4
• /
• pp.35-41
• /
• 2014

The height and capacity of the thermal storage tank can be decided by the altitude and heat load of the heat supply area. Evaporation in heat pipe can be prevented by pressurizing it with the hydraulic head of the thermal storage tank. In addition, it absorbs the expanded volume from the temperature changes and supplies water to the pipelines in case of the shortage of water. One of the most important roles of the thermal storage tank is a stable heat supply facility. It can control the heat demand by accumulating the surplus heat and supplying in changing heat demand time. The purpose of this thesis is to be helpful for the operation and maintenance of the thermal storage tanks. The study has been carried out for 18 thermal storage tanks, which have been used polyurethane foam as insulation, among 27 tanks in district heating plants. The characteristics of the insulation materials, the reasons for the damages of the insulation and how impact the insulation damages to the corrosion of the thermal storage tank have been studied.

• Journal of Bio-Environment Control
• /
• v.26 no.4
• /
• pp.353-360
• /
• 2017

In this study, the design and performance test of the air to water heat pump capable of producing hot water for greenhouse heating by using the surplus solar heat inside the greenhouse and the air heat outside greenhouse as the selective heat source were conducted. The heat storage operations using the surplus solar heat and the outside air heat were designed to be switched according to the setting temperature of the greenhouse in consideration of the optimum temperature range of the crop. In the developed system, it was possible to automatically control the switching of heat storage operation, heating and ventilation by setting 12 reference temperatures on the control panel. In the selective heat storage operation with the surplus solar heat and outside air heat, the temperature of thermal storage tank was controlled variably from $35^{\circ}C$ to $52^{\circ}C$ according to the heat storage rate and heating load. The heat storage operation times using the surplus solar heat and outside air heat were 23.1% and 30.7% of the experimental time respectively and the heat pump pause time was 46.2%. COP(coefficient of performance) of the heat pump of the heat storage operation using the surplus solar heat and outside air heat were 3.83 and 2.77 respectively and was 3.24 for whole selective heat storage operation. For the comparative experiment, the heat storage operation using the outside air heat only was performed under the condition that the temperature of the thermal storage tank was controlled constantly from 50 to $52^{\circ}C$, and COP was analyzed to be 2.33. As a result, it was confirmed that the COP of the heat storage operation using the surplus solar heat and outside air heat as selective heat source and the variable temperature control of the thermal storage tank was 39% higher than that of the general heat storage operation using the outside air heat only and the constant temperature control of the thermal storage tank.