• Article

    Performance Experiment of Multi-Effect Diffusion Distiller with Extruded Wick-Free Plate

    압출 가공 wick-free plate가 적용된 다중효용확산 태양열 증류기의 성능 실험

    Lee Ga-Ram ・ Lim Byung-Ju ・ Choi Seok-Min ・ Park Chang-Dae

    이가람・임병주・최석민・박창대

    We have developed a wick-free plate (WFP) in which a groove pattern is applied to the surface of a plate to replace ... + READ MORE
    We have developed a wick-free plate (WFP) in which a groove pattern is applied to the surface of a plate to replace the wick-plate, which is a key component of a multi-effect diffusion distiller (MEDD). Wicks and plates act as an evaporation surface and a condensation surface, respectively, in MEDD. However, the wick-plate structure has several problems, such as laborious manufacturing processes and lower durability. Therefore, in this study, WFPs were manufactured using the extrusion method, and MEDD with WFPs was experimentally evaluated. The extrusion method had a lower processing cost and better corrosion-resistance surface than the etching process that was employed in our previous study. The extruded WFP could lower the manufacturing cost by 77% compared to the etched WFP, and had the advantage of absorbing more solar radiation energy by lowering the installation inclination angle by 10°. After fabricating the triple-effect MEDD with the extruded WFPs, an indoor performance experiment was conducted. The results of the solar thermal performance test indicated that WFP-MEDD at 11.7 MJ/(m2 · d) of thermal energy produced 3% higher freshwater than the existing MEDD with a wick-plate. - COLLAPSE
    February 2021
  • Article

    Study on Solar Air Thermal Performance Test based on International Standard

    국제 기준 공기식 태양열 집열기 열 성능 평가 연구

    Kim Yu-Jin ・ Kim Ki-Bong ・ Lee Euy-Joon ・ Kang Eun-Chul

    김유진・김기봉・이의준・강은철

    Solar air thermal collectors are one of the technologies used to improve the efficiency of fresh air heating system in building spaces ... + READ MORE
    Solar air thermal collectors are one of the technologies used to improve the efficiency of fresh air heating system in building spaces. Solar air collectors have the advantage of preventing freezing and overheating problems when compared with solar water collectors. However, thus far, there have been no harmonized thermal performance test facilities or round robin tests (RRT) based on the international standard ISO 9806 in Korea. In this study, an ISO 9806 thermal performance test facility was introduced and designed. In addition, an RRT was conducted based on ISO 9806 and compared to RRT sample Exova performance test results to verify the consistency of the thermal performance. The thermal efficiency ranged 36.06% ~ 72.02% depending on a change flow rate change of 36.6 ~ 182.9 m3/(hr·m2), respectively. The RRT was successfully conducted to compare the results of the Exova thermal performance test. A comparison between the Exova and KIER tests showed a relative error of 5.51% and 6.42% for ambient wind velocities of 1.0 and 1.8 m/s, respectively. - COLLAPSE
    February 2021
  • Article

    Study on Electrical and Thermal Performance Assessment of an Air-Type PVT Collector with Perforated Baffle

    타공 베플이 적용된 공기식 PVT 컬렉터의 실험을 통한 열·전기성능 평가 연구

    Yu Ji-Suk ・ Lee Kil-Seon ・ Kim Jin-Hee ・ Kim Jun-Tae

    유지숙・이길선・김진희・김준태

    BIPV (Building Integrated Photovoltaic) is a building envelope technology that converts solar energy into electrical energy, but heat is dissipated at the ... + READ MORE
    BIPV (Building Integrated Photovoltaic) is a building envelope technology that converts solar energy into electrical energy, but heat is dissipated at the back of the BIPV module during the production of electrical energy. However, PVT collectors are devices that produce electricity on the front of the PV and concurrently use heat generated from the back of the PV module. Therefore, in buildings that require heating loads, the PVT system can use both electrical and thermal energies directly; hence, its solar energy utilization rate is higher than that of the BIPV and solar thermal systems. In this study, a new PVT collector using air as the heating medium was newly designed and fabricated, and the thermal and electrical performances were analyzed through outdoor experiments. A baffle applied to the air layer in the collector was designed earlier to improve the thermal performance through CFD simulation analysis. This study analyzed the thermal and electrical characteristics according to the inlet flow rate, solar radiation intensity, and temperature at the back of the PV module of a new type of air-type PVT collector. Consequently, when the inlet flow rate of the collector increased to 100 ~ 200 m3/h, it was confirmed that the thermal efficiency was 22.7 ~ 50% and the electrical efficiency was 15.75 ~ 16.54%. - COLLAPSE
    February 2021
  • Article

    A Study on a Method for Deriving the Standard Coefficient of the Heating Energy Saving Rate Predicted by a Replacement of High-insulation Windows

    고단열 창호로의 교체를 통해 예측되는 난방에너지 절감률 표준계수 도출 방법에 관한 연구

    Oh Min-Seok ・ Kim Gi-Cheol

    오민석・김기철

    The purpose of this study is to compare the heating energy requirements according to the window performance and derive standard coefficients that ... + READ MORE
    The purpose of this study is to compare the heating energy requirements according to the window performance and derive standard coefficients that can be used to easily calculate the savings. In Korea, the total amount of energy consumed by buildings is restricted by the Green Building Creation Support Act and building standards for the energy-saving design have been proposed. In addition, the energy-saving design criteria for buildings suggest insulation performance standards for windows and doors to prevent heat loss in buildings. Windows are the most important area of heat loss in the main building, and are a priority target for energy efficiency. High-efficiency insulating windows can reduce the heat load by minimizing the amount of energy loss through the application of a thermal bridge blocking material for double-glazed windows and window frames. Therefore, in this study, the effect of the change in window performance on the heating energy demand was checked using the building energy evaluation software ECO2, and standard coefficients for calculating the reduction rate were derived. - COLLAPSE
    February 2021
  • Article

    Analysis of Thermal and Electrical Performance for Air-Type PVT Collectors According to PV Module Cell Ratios

    PV 모듈의 셀 면적 비에 따른 공기식 PVT 컬렉터의 열 및 전기성능 비교·분석 연구

    Lee Kil-Seon ・ Yu Ji-Suk ・ Kim Jin-Hee ・ Kim Jun-Tae

    이길선・유지숙・김진희・김준태

    The air-type photovoltaic / thermal (PVT) collector is a solar collector that acquires heat generated from the back of the PV module through ... + READ MORE
    The air-type photovoltaic / thermal (PVT) collector is a solar collector that acquires heat generated from the back of the PV module through the circulation of air behind the collector, while the PV module uses solar energy to produce electrical energy. In this process, electricity is produced through PV modules, and heat energy is produced through a heat collection process using air as the heat medium. According to the PV cell ratio, air-type PVT collectors differ in the collector’s thermal and electrical performance. The higher the PV cell ratio of the PV module, the more is the ratio of PV cells per unit area, thereby increasing the total electricity generation of the collector. However, when the PV cell ratio is lowered, the glass to back sheet (GtoB) transparent type PV module increases the area of the light-permeating part. Therefore, the air heat behind the PV module increases, thereby improving the thermal performance of the collector. In this study, outdoor testing was conducted in accordance with the test conditions of ISO9806:2017 to investigate the thermal and electrical performance of an air-type PVT collector. A comparative experiment was carried out for: (i) Case 1 (PV cell ratio of 0.9) with a perforated baffle, and (ii) Case 2 (PV cell ratio of 0.67) with a lower PV cell ratio to improve thermal performance. Based on the inlet flow rate and the PV cell ratio of air-type PVT collectors, the thermal and electrical efficiencies were analyzed and compared. - COLLAPSE
    February 2021
  • Article

    Study on Surface Temperature Variation of Several Pavement with Snow Melting System Using Hot Water Piping

    온수 배관방식 도로융설 시스템의 포장에 따른 표면 온도변화에 관한 연구

    Kim Jin-Ho

    김진호

    Snow melting system in road is a device which prevents being frozen for safety. If the snow melting system with piping is ... + READ MORE
    Snow melting system in road is a device which prevents being frozen for safety. If the snow melting system with piping is used, the economical benefit is growed and the geothermal unbalance for years is able to be solved, also. Because the snow melting system with piping is different with the electric snow melting system in design aspects, it requires additional considerations such as kinds of pipe, heat medium and flowrate etc. In this paper, for predicting the heat dissipation to air side of the snow melting system of piping, CFD simulation are performed. And the variation of road surface temperature along time for thickness and kinds of the pavement is investigated. Flowrate of heat medium is not big effect on heat dissipation in same diameter of pipe. As the diameter is increased from 25A to 32A, the amount of heat dissipation is increased from 149 to 215 W/m2. If the pipe spacing is increased or reduced by 16.7 % based on 150 mm, the amount of dissipation is increased or decreased by 20% or 18%. It can be seen that the top layer pavement largely affects on the time when the road surface temperature reaches 0°C. - COLLAPSE
    February 2021
  • Article

    Empirical Analysis and Thermal Performance Evaluation for Building Integrated Photovoltaic System

    건물일체형 태양광발전(BIPV) 시스템 실증분석 및 열성능 평가

    Cho Ga Young・ Eom Jaeyong・ Oh Min- seok・ Kim Eui-Jong

    조가영・엄재용・오민석・김의종

    The Seoul Metropolitan Government announced a comprehensive plan for “Solar City, Seoul,” which is aimed at 1GW of power for 1 million ... + READ MORE
    The Seoul Metropolitan Government announced a comprehensive plan for “Solar City, Seoul,” which is aimed at 1GW of power for 1 million households by 2022. Subsidies for the installation of BIPV(Building Integrated Photovoltaic Systems) in private buildings were expanded in 2020. It is therefore necessary to consider the building-integrated photovoltaic performance to harmonize with urban landscapes using renewable energy sources to realize zero-energy buildings. A field experiment was conducted to investigate the conditions of the BIPV, and the performance impact factors were analyzed. The results showed that the general glass, BIPV intermediate space, and internal surface of the BIPV temperature increased when insulation was added to the BIPV back panel in the spandrel part. The temperature increase in the Spandrel part is mainly caused by solar radiation, and the intermediate space temperature of the general glass rises higher than that of the BIPV module installation. The performance of the BIPV system was evaluated through a simulation. The simulation results showed that the temperature of the solar cell during BIPV generation depended on the energy balance of the effective solar radiation and ambient temperature. In the future, a comprehensive review of the module and material performances, such as the power generation and efficiency, will be required based on experimental verification. - COLLAPSE
    February 2021
  • Article

    Analysis of Heat Transfer Performance According to Installation Conditions of Various Protrusions with Non-uniform Cross-section in Air Space of Air-Type PV/T System

    공기식 태양광/열 집열기 내 공기층에서 비균일 단면을 갖는 돌출부 설치 조건에 따른 전열 성능에 관한 분석

    Moon Kwang-Am ・ Choi Hwi-Ung ・ Kim Young-Bok ・ Son Chang-Hyo ・ Yoon Jung-In ・ Choi Kwang-Hwan

    문광암・최휘웅・김영복・손창효・윤정인・최광환

    Air-type photovoltaic/thermal (PV/T) collectors attached to ducts beneath the solar panels are devices that can recover heat while the panel ... + READ MORE
    Air-type photovoltaic/thermal (PV/T) collectors attached to ducts beneath the solar panels are devices that can recover heat while the panel cools. By contrast, water-type PV/T is easily used because the air of an air-type PV/T has a lower heat capacity than water. A number of studies have been conducted on the installation of ribs as a way to increase the heat recovery capacity of air through ducts. In this study, a protrusion with a non-uniform cross-section was selected to increase the contact area of the air side as well as to promote turbulence. A computational fluid dynamics (CFD) analysis was conducted to confirm the heat transfer performance and the characteristics of the pressure drop according to different shape conditions. As a result, the heat transfer performance was improved by 1.3- to 1.9-fold depending on the conditions of the protrusion installation. However, the pressure drops also increased from 2.534- to 4.685-fold. It is therefore necessary to identify those factors of the thermal hydraulic performance that consider both the heat transfer and pressure drop. As a result, the maximum heat-recoverable shape condition achieved the largest performance coefficient value of 1.24 when e/H = 0.16, P/e = 20, and Wp/e = 5. - COLLAPSE
    February 2021
  • Article

    A Review of the Current Status and Examples of Color Type BIPV Design-Mainly in Switzerland

    컬러형 BIPV 디자인 현황 및 사례 고찰 -스위스 지역을 중심으로

    Lee Eung-Jik

    이응직

    Reducing CO2 emissions and using renewable energy in buildings is a new trend in global architecture. BIPV is establishing itself as ... + READ MORE
    Reducing CO2 emissions and using renewable energy in buildings is a new trend in global architecture. BIPV is establishing itself as an architectural refinement of new corresponding technologies, and in particular, an architectural design solution is being sought for color-type BIPV. Therefore, this study aims to contribute to the extension and application of a BIPV design by capturing the realistic level and current status of a color type BIPV, investigate and analyze advanced cases, and infer the characteristics of the BIPV. A common feature resulting from this is the implementation of different colors by processing the front glass of the module on the basis of a highly efficient monocrystalline module. In this case, the existing PV color and texture are not displayed. This means there is no problem with the design harmonizing with the architecture itself or with the urban esthetics. The SSG point fixation is applied to all modules such that the outside surface appears to be homogeneous and smart, whereas the ventilation on the back of the module prevents a decrease in efficiency. - COLLAPSE
    February 2021
  • Article

    Annual Analysis of Thermal and Electrical Performances of PV/T Solar Hot Water Systems in Apartments

    공동주택에 적용된 PV/T 태양열 급탕시스템 연간 열 및 발전성능 분석

    임희원・이왕제・윤종호・조성구・백남춘・신우철

    Lim Hee-Won ・ Lee Wang-Je ・ Yoon Jong-Ho ・ Cho Sung-Goo ・ Baek Nam-Choon ・ Shin U-Cheul

    A PV/T solar collector, wherein a photovoltaic module and a solar collector are combined into a single component, is considered to ... + READ MORE
    A PV/T solar collector, wherein a photovoltaic module and a solar collector are combined into a single component, is considered to be highly reliable, durable, and economically feasible. Additionally, zero-energy buildings have recently drawn significant attention. In this study, the dynamic behavior and energy performance of a PV/T solar hot water system employed in a twenty-storey apartment were analyzed. The said system comprises three 25 EA (a total of 75 EA) PV/T solar collectors and a 15.6 ton storage tank. The TRNSYS 17 software was employed as a simulation tool for conducting the analysis, and the national reference standard weather data (TMY3) of Daejeon, South Korea was incorporated as meteorological data. The obtained results indicate that if the available space is limited and if the aspect of energy efficiency is considered, the usage of PV/T solar hot water systems that simultaneously produce thermal energy and electrical energy can be more advantageous than the usage of standard photovoltaic or solar hot water systems. - COLLAPSE
    February 2021