• Journal of the Korean Solar Energy Society
• /
• v.31 no.5
• /
• pp.9-18
• /
• 2011

태양광열 복합 시스템(photovoltaic/thermal hybrid solar system, PV/T)은 태양광 모듈 및 태양열 집열판의 단일화를 통한 전기 및 열에너지의 동시 생산이 가능하도록 구성되고 기존 태양광 모듈의 온도 상승에 따른 효율 저하의 문제점을 보완 및 발생하는 열을 회수하여 온수 생산이 가능한 장치이다. 본 연구에서는 액체형 PV/T 시스템의 대표적인 두 형태인 박스형과 튜브형의 성능 검증을 위하여 수학적 모델링을 통한 두 시스템의 열 및 전기적 성능을 비교 분석하였다. 모델링은 에너지 평형식을 이용하여 시간에 따른 각 부분의 온도의 변화를 예측할 수 있도록 수립되었으며 계산된 결과를 기준으로 전기, 열, 및 전체효율을 도출해 내고, 이를 바탕으로 두 시스템의 성능을 분석하였다. 시뮬레이션 결과를 바탕으로, 박스형 PV/T 시스템의 최고 온수 온도는 $52^{\circ}C$로 예측되었고, 반면에 튜브형은 $48^{\circ}C$에 머물렀다. 또한 열효율은 박스형이 최대 51%, 튜브형이 41%, 전기효율은 박스형이 약 14%, 그리고 튜브형이 13%로 나타났으며, 전체효율은 박스형이 73%, 그리고 튜브형이 64%로 나타나 박스형 PV/T 시스템이 튜브형보다 더 나은 성능을 가지는 것으로 예측되었다. 이는 박스형이 튜브형보다 태양광 모듈과 온수와의 접촉면적이 넓어 더 많은 열전달이 발생하기 때문으로 사료된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.9
• /
• pp.826-835
• /
• 2007

Solar heat flux data is needed for thermal load prediction of launch vehicle. In order to predict the solar flux, several solar flux models have been compared and a new model is developed. Most of the models can predict well the direct solar flux, but show some errors in the scattered solar flux. The newly developed model considered isotropic and anisotropic scattered solar fluxes, and the predicted solar flux agreed well with the measured. Because the present model can be used at any longitude, latitude, day and altitude, the model would be an useful tool to predict the thermal load of the launch vehicle and the vehicles which have to consider the solar heat.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.11a
• /
• pp.187-192
• /
• 1999

전 세계적으로 무분별한 화석에너지 사용에 따른 환경오염 문제와 에너지원의 고갈로 인하여 태양에너지는 대체에너지원으로 가장 유용한 에너지원이다. 대체에너지원으로의 태양에너지는 다양한 이용분야가 개발되어 실용화되고 있는데 그 중에서 온수급탕을 위한 연구로 자연형 태양열 시스템과 상변화형 시스템이 주류를 이루고 있다. 자연형 시스템의 개발과 실용화로 얻어진 기술을 바탕으로 기후에 적합한 상변화를 이용하는 시스템 개발을 추진하고 있는 실정이다.(중략)

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.1
• /
• pp.28-34
• /
• 2019

Solar energy is one of the most abundant renewable energy sources on Earth but there are restrictions on the use of solar thermal energy due to the time-discrepancy between the solar-rich season and heating demand. In Europe and Canada, a seasonal solar thermal energy storage (SSTES), which stores the abundant solar heat in the summer and uses the heat for the winter heating load, is used. Recently, SSTES has been introduced in Korea and empirical studies are actively underway. In this study, a $2,000m^2$ flat plate type solar collector and $20,000m^2$ of borehole thermal energy storage (BTES) were studied for a greenhouse in Hwaseong City, which has a heating load of 2,164 GJ/year. To predict the dynamic performance of the system over time, it was simulated using the TRNSYS 18 program, and the solar fraction of the system with the control conditions was investigated. As a result, the solar BTES system proposed in this study showed an average solar fraction of approximately 60% for 5 years when differential temperature control was applied to both collecting solar thermal energy and discharging BTES. The proposed system simplified the configuration and control method of the solar BTES system and secured its performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.6
• /
• pp.556-565
• /
• 2004

We have experimented an actual solar water heating system acquiring real data for one year period. On the basis of the operation data, it is necessary to predict the system performance such as collector efficiency and solar fraction, and to analyze the economical efficiency for system optimal design. To estimate the performance of actual systems through simulation, valid modelling for components consisting of the system should be accompanied. The present study is focused on the modelling for load patterns and operating control conditions. We proposed two load models: concentration model which gathers real loads as a meaningful group and distribution model which disperses real loads with time. If grouping of the load distribution is suitable, the predicted values by the concentration model approaches to those by the distribution model close to actual load pattern apparently. As a result, both of them are in good agreement with those by experiment.

• Proceedings of the Korean Information Science Society Conference
• /
• 2012.06b
• /
• pp.10-12
• /
• 2012

태양광 발전이란 햇빛을 전기로 전환하는 친환경 차세대 대체 에너지 생산기술로 오래 전부터 주목받아 왔다. 태양광 발전에는 태양열을 모아 이를 발전에 사용하는 태양열 집중방식과 광전효과를 이용하여 직접 전기를 생산하는 태양광 발전으로 나뉘는데 반도체 생산 기술의 발달에 따라 점차 태양광 발전의 비중이 증가하고 있다. 태양광 발전의 효율은 크게 일사량과 온도에 의해 결정되는데 두 요소에 따라 효율의 변동성이 크기 때문에 정확한 발전 효율을 측정하는 일은 어렵다. 본 논문에서는 발전소에서 수집된 온도와 일사량, 발전량 데이터를 이용하여 선형 회기 분석과 확률적 모델링을 사용해 현재 발전량의 신뢰도를 계산하고 발전모듈 점검의 필요성을 판단하는 방법을 제시하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.1
• /
• pp.56-64
• /
• 2002

Thermally induced vibration response of composite thin-walled beams is investigated in this paper. The flexible spacecraft appendages modeled as thin-walled beam incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constitute materials. Thermally induced vibration responds characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending lagwise bending coupling resulting from directioal properties of fiber reinforced composite materials and ply stacking sequence. A coupled thermal structure gradient is investigated.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.10
• /
• pp.989-996
• /
• 2011

An understanding of the concentrated solar flux is critical for the analysis and design of solar-energy-utilization systems. The current work focuses on the development of an algorithm that uses the Monte Carlo ray-tracing method with excellent flexibility and expandability; this method considers both solar limb darkening and the surface slope error of reflectors, thereby analyzing the solar flux. A comparison of the modeling results with measurements at the solar furnace in Korea Institute of Energy Research (KIER) show good agreement within a measurement uncertainty of 10%. The model evaluates the concentration performance of the KIER solar furnace with a tracking accuracy of 2 mrad and a maximum attainable concentration ratio of 4400 sun. Flux variations according to measurement position and flux distributions depending on acceptance angles provide detailed information for the design of chemical reactors or secondary concentrators.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.04a
• /
• pp.223-228
• /
• 2011

The volumetric solar receiver is a key element of solar power plants using air. The solar flux distribution inside the receiver should be a priori known for its heat transfer modeling. Previous works have not considered characteristics of the solar flux although they change with radiative properties of receiver materials and receiver geometries. A numerical method, which is based on the Monte Carlo ray-tracing method, was developed in the current work. The solar flux distributions inside multi-channeled volumetric solar receivers were calculated when light is concentrated at the KIER solar furnace. It turned out that 99 percentage of the concentrated solar energy is absorbed within 15 mm charmel length for the charmel radius smaller than 1.5 mm. If the concentrated light is assumed to be diffuse, the absorbed solar energy at the charmel entrance region is overpredicted while the light penetrates more deeply into the charmel. The developed method will help understand the solar flux when only a part of concentrated light is of interest. Furthermore, if the presented results are applied for heat transfer modeling of multi-channeled volumetric solar receivers, one could examine effects of receiver charmel properties and shape on air temperature profiles.

• Journal of IKEEE
• /
• v.23 no.2
• /
• pp.380-387
• /
• 2019

In recent years, solar energy PV/T research has been actively pursued by complementing solar heat acquisition and solar energy acquisition, and PV/T energy efficiency is generally excellent. In this study, the annual energy demand is calculated based on one building, and the energy production when PV / T installed on the roof and the energy production when PV are installed are compared and analyzed by simulation case. In conclusion, Busan which is the southern province in Korea, has the largest amount of energy generation, and introducing the concept of sharing surplus energy, excluding energy demand from generation. As a result, it can be supplied up to 3.3 households.