Performance Analysis of Roof-Integrated Water-Type PVT Heating System

Jin-Hee Kim,Jun-Tae Kim 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.3

The Photovoltaic-thermal (PVT) collector is a single device that combines a photovoltaic module and a solar thermal collector, producing thermal energy and generating electricity simultaneously. PVT collectors produce more energy per unit surface area than side-by-side PV modules and solar thermal collectors. They can be classified into air-type and water-type collectors according to the thermal medium used for collecting heat in the collector. The water-type PVT collector tends to show better thermal performance than the air-type PVT collector. The thermal energy from water-type PVT collectors can be used in buildings for hot water and heating. It is important to understand the overall energy performance of building heating systems that work in conjunction with PVT collectors to demonstrate the potential of their building applications. The aim of this study is to analyze the performance of heating system combined with PVT collectors that are integrated on a building roof. For this study, a 1.5kWp roof-integrated water-type PVT system was installed onto an experimental house and was incorporated into its heating system. The experimental results showed that the total heat gain from the collector is 9.7 kWh, while the average thermal and electrical efficiency levels of the system are 30% and 17%, respectively. It was also found that the heating energy for the house can be reduced by 47%, as the heat gained from roof-integrated PVT system pre-heated the water used for heating system.

Performance analyses of a steam condensation tube immersed in a saturated water pool: Effects of tube inclination

Amidu, Muritala Alade,Park, Junseok,Park, Youngjae,Lim, Changhwan,Jung, Satbyoul,Kim, Hyungdae Elsevier 2017 Nuclear engineering and design Vol.323 No.-

<P><B>Abstract</B></P> <P>Two-phase heat exchanger immersed in a passive containment cooling water storage tank (PCCWST) is a key component of the passive containment cooling system (PCCS) in light water reactors. Condensation and boiling heat transfer phenomena taking place on the inside and outside walls are crucial to the performance of the heat exchanger tube. The performances of such phenomena can be readily affected by the inclination angle of the heat exchanger tube under buoyancy-driven convection conditions in a PCCWST. However, to date no systematic examination of the effects of inclination angle on pool heat exchanger performance has been reported. This paper presents the results of numerical and experimental analyses of how inclination angle affects the performance of a single steam condensation tube immersed in a saturated water pool. To concurrently predict the two-phase heat transfer processes inside and outside the heat exchanger tube, an explicit heat structure coupling of two thermal-hydraulic codes was implemented using open media models. An experimental facility was also constructed to test a single-tube heat exchanger under the same conditions as the simulation. A comparison of simulation data and experimental results obtained for the reference case (tube inclination of 30°) confirmed that the coupled code could predict the heat transfer rate in the pool heat exchanger within the error limits of the experimental measurements. In light of this, additional simulations and experiments were conducted at varying inclination angles, from 3° to 90°. The results of simulations and experimental studies revealed that the heat transfer rate of a heat exchanger tube in a saturated pool is hardly influenced by tube inclination. Although an increase in inclination angle caused the vapor slug to spread around the heat exchanger tube surface, preventing liquid from getting to the surface of the tube, thereby decreasing boiling heat transfer coefficients, this was compensated for by an increase in condensation heat transfer coefficients as the inclination angle increased as a result of accelerated condensate liquid film in the tube. Thus, the overall effect of inclination angle on the thermal performance of a single-tube pool heat exchanger is inconsequential.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Performance of a single condensation tube immersed in a saturated pool was studied. </LI> <LI> Explicit heat structure coupling of CUPID and MARS codes was implemented. </LI> <LI> Simulations using coupled code and validation experiments were performed. </LI> <LI> Inclination angle has no significant effect on performance of a condensation tube. </LI> </UL> </P>

중앙난방 공동주택 적용을 위한 난방온수 간접공급 열 교환 유닛의 난방성능 개선 효과

정창호 水原大學校 2020 論文集 Vol.34 No.-

The heating load of residential buildings in Korea continues to decrease. Residents' demands for heating in residential buildings are becoming more complex and diverse. On the other hand, the composition and heat medium conditions of radiant floor heating panels, which are applied to most domestic residential buildings, are routinely applied without major changes compared to when the system was introduced in Korea. In addition, the heating control methods currently generally applied are also limited in terms of supplying the required heat for space heating over time. These conditions can cause temporary discomfort or unnecessary waste of energy during heating operations. In this study, the indirect heat interface unit was selected as an alternative to supplying the needed heat for individual house in central heating residential building. And then, the heating performance was analyzed and the feasibility of this system was evaluated.

전기버스용 히트펌프 시스템 난방 운정 특성에 관한 연구

전한별(Han-Byeol Jeon),김우근(Woo-Geun Kim),이호성(Ho-Seong Lee),김윤성(Yoon-Sung Kim),조중원(Chung-Won Cho) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

Heating performance of a heat pump system for electric buses was studied experimentally. In order to know heating performance characteristics of a heat pump, it was test under various operating conditions such as electric compressor speed and exterior temperature. Although heating capacity improves as electric compressor speed increase, COP for heating does not improves. This indicates that size of exterior heat exchanger restrict the amount of heat absorption, which inhibited the system COP for heating.

Heat Transfer Performance Optimization of Rectangular Channel with Truncated-root Ribs

Ky-Quang Pham,Van-Minh Le,Cong-Truong Dinh 한국유체기계학회 2022 International journal of fluid machinery and syste Vol.15 No.2

Cooling designs inside the gas turbine blades of aircraft engines are aimed to solve a problem that has existed since the very beginning of the aerospace industry. Since the working environment of turbine blades is extremely harsh when the temperature can rise to 2000K, which is considered a huge challenge for any materials. Therefore, cooling designs such as rib turbulators have always been researched and optimized for better heat transfer enhancement in the cooling mechanism of turbine blades. In this study, a geometric optimization of the rib turbulators inside a rectangular channel was performed with the aim to maximize heat transfer performance. This study investigated the effect of four rib configurations on the heat transfer efficiency of the channel, which include square, truncated-root, convergent truncated-root, and divergent truncated-root rib. Thereby, a module of coupling Python and OpenFOAM was developed to automatically perform the optimization of truncated-root rib design at Reynolds number of 37,000 with design variables are the upstream and downstream height with Powell optimization method. The aim is to figure out the point where the maximum heat transfer performance of the channel is achieved. The study presented in a specific, productive, and accurate way the factors that directly and indirectly affect the heat transfer performance of the channel, thereby giving the optimal results that the channel has the highest heat transfer performance of the presented designs. The results show that the highest heat transfer performance of the optimized design is 12.45% higher than the standard square ribs case.

Heating performance characteristics of a dual source heat pump using air and waste heat in electric vehicles

Ahn, J.H.,Kang, H.,Lee, H.S.,Jung, H.W.,Baek, C.,Kim, Y. Applied Science Publishers 2014 APPLIED ENERGY Vol.119 No.-

A heat pump has been considered as an alternative to an electric heater to increase the efficiency of the heating unit in electric vehicles. However, the heating performance of a single source heat pump has yet to be improved at low outdoor temperatures. This study investigates the feasibility of a dual source heat pump using both air and waste heat in electric vehicles. The performance of the dual source heat pump was measured at various operation modes: air source-only, waste heat-only and dual heat source. The heating performance of the dual source heat pump was higher than those of the single source heat pumps. In addition, an alternating single mode operation of air source-only and waste heat-only modes was proposed to improve performance at low outdoor air temperatures.

강제대류에서 히트싱크의 성능평가를 위한 열해석 연구

이봉구,이민 한국기계기술학회 2015 한국기계기술학회지 Vol.17 No.6

The heat generated by the internal electro-mechanical device is not transferred to the outside, to degrade the performance of the electronic device, or the cause of failure. Heat sinks are used to control the heat. Thermal performance of the heat sink of the pine type and pin type was analyzed using ANSYS software. The numerical results were compared with the thermal performance of the pine type and pin-type heat sink. The results of the numerical simulation showed that Pine type heat sink showed an approximately 58 percent better heat transfer rate with forced convection than Pin type heat sink.

한랭지(몽골) 지열 히트펌프 시스템의 난방 성능 분석

손병후(Byonghu Sohn),최재호(Jae Ho Choi),민경천(Kyung Chon Min) 대한설비공학회 2015 설비공학 논문집 Vol.27 No.1

Geothermal heat pump (GHP) systems have become an efficient alternative to conventional cooling and heating methods due to their higher energy using efficiency. These systems use the ground as a heat source in heating mode operation and a heat sink in cooling mode operation. The aim of this study is to evaluate the heating performance of the GHP system for a residential building (420 m2) in Ulaanbaatar, Mongolia. In order to demonstrate the feasibility of a sustainable performance of this system, we installed the water-to-water geothermal heat pump with ten vertical ground heat exchangers and measured operation parameters from October 19, 2013 to March 26, 2014. The results showed that the entering source temperature of brine from the ground heat exchangers was in a range of the design target temperature of -10℃ for heating. For total values of the representative results, the ground heat exchangers extracted heat of 53.51 MWh from the ground. In addition, the GHP system supplied heat of 83.55 MWh to the building and consumed power of 30.27 MWh. Consequently, the average heating seasonal performance factor (SPFh) of the overall system was evaluated to be 2.76 during the measurement period of the heating season.

지열 난방시스템을 이용한 분만돈사의 난방효과 분석

최희철,박재홍,송준익,나재천,김민지,방한태,강환구,박성복,채현석,서옥석,유영선,김태원,Choi, H.C.,Park, Jae-Hong,Song, J.I.,Na, J.C.,Kim, M.J.,Bang, H.T.,Kang, H.G.,Park, S.B.,Chae, H.S.,Suh, O.S.,Yoo, Y.S.,Kim, T.W. 한국축산환경학회 2010 축산시설환경학회지 Vol.16 No.3

Geothermal heat pump system (GHPS) is an energy-efficient technology that use the relatively constant and renewable energy stored in the earth to provide heating and cooling. With the aim of using GHPS as a heating source, it's possibilities of application in farrowing house were examined by measuring environmental assessment and sow's performance. A total of 96 sows were assigned to 2 pig housings (GHPS and conventional housing) with 48 for four weeks in winter season. During the experimental period, indoor maximum temperature in GHPS-housing was measured up to $26.7^{\circ}C$, average temperature could maintain $21.2^{\circ}C$. The mean value of dust levels and $CO_2$, $NH_3$ and $H_2S$ gas emissions were decreased in GHPS-housing compare with those of conventional housing. Litter size, birth weight, parity and weaning weight did not differ between housings. However, feed intake of sow in GHPS-housing was lower than that of conventional housing. In energy consumption for heating, electric power consumption increased in GHPS-housing than the conventional housing, a 2,250 kwh increase, whereas there is no fuel usage for heater in GHPS-housing. Amount of ground water circulated for heating in cold weather for earth heat exchanger was 8.4-12.9 ton per day. In conclusion, GHPS may have environmental benefits and effectiveness of heating in farrowing housing and affect the performance in sows. 지열히트펌프를 이용한 축사용 냉난방시스템을 개발하고 농장 적용성을 검토하기 위하여 330 $m^2$ 규모의 농장에 개발 시스템을 설치하여 돈사에서의 난방 이용효과를 분석하였으며, 그 결과는 다음과 같다. 1. 지열 난방시 부하량은 24,104 kcal이었으며 농장시험 지열이용 냉난방시스템의 제원은 히트펌프 용량은 10 USRT 였으며, 상부 덕트형 30,000 kcal 홴코일유니트를 사용하였으며 FCU의 풍량은 90 $m^3$/분 이었다. 2. 지열 난방 1주령시 외부 최고기온 $14.2^{\circ}C$, 최저 영하 $9.3^{\circ}C$일때 시험구는 평균 $21.5^{\circ}C$로서 대조구 $19.8^{\circ}C$에 비하여 높았다. 3. 지열 난방 시험돈사의 먼지 농도는 PM10 185.3, PM2.5 40, PM1.0 $23.4{\mu}g/m^3$으로 대조구 PM10 481.4, PM2.5 47, PM1.0 $28.2{\mu}g/m^3$에 비하여 낮았다.4. 지열 난방 시험돈사의 유해가스농도는 $CO_2$ 1,470, $NH_3$ 10.6, $H_2S$ 0.05 ppm으로서 대조구 $CO_2$ 2,025, $NH_3$ 23.3, $H_2S$ 0.69 ppm에 비하여 유의적으로 (p<0.05) 낮았다. 5. 지열난방시 복당 이유두수는 10.5두로 대조구 10.4두에 비하여 높았으며 이유시체 중도 6.93 kg으로 대조구 6.86 kg에 비하여 컸으며 특히 온도가 낮은 대조구에서 모돈사료 섭취량이 99.6 kg으로 시험구 88.2 kg 보다 유의적으로 (p<0.05) 많았다. 6. 지열 난방시 외부기온과 지하수 순환량에 있어서 외부기온이 낮을 경우 1일간 8.4-12.9톤으로 지하수 순환량이 많았다.

공조기용 Corrugate Fin-Tube 열교환기의 냉난방 및 착상성능

김주혁(Ju Hyok Kim),김홍성(Hong Sung Kim),이한춘(Han Choon Lee),사용철(Yong Cheol Sa),오세기(Sai Kee Oh) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6