• Journal of the Korean Solar Energy Society
• /
• v.37 no.5
• /
• pp.39-47
• /
• 2017

In a hot water system using solar energy, solar heat is not simply collected by the heat collecting plate, but by heat exchange between the solar collector (flat or vacuum type) and the hot water storage tank. Therefore, the amount of collected solar energy depends on the hot water usage patterns that determine the temperature of the thermal storage tank. Also, if the temperature of the hot water stored in the storage tank exceeds the dangerous temperature during the summer, the heat must be released for safety. If the temperature of the hot water in the storage tank is low, it is necessary to heat by the auxiliary heat source. In this study, three buildings are defined as hotel, swimming pool, and school facilities. And we calculated the released heat energy, auxiliary heat source, and pure storage heat energy based on different hot water usage patterns and installation angle of the solar collectors.

• Journal of Energy Engineering
• /
• v.21 no.4
• /
• pp.435-443
• /
• 2012

The combination of space shortage and the high population density concentrated in urban areas of South Korea has resulted in the growth of large-scale high-rise residential complexes, naturally affecting water and hot water usage patterns as well. But the current designs for water and hot water supply in South Korea rely mostly on international design standards and data calculated on site due to the severe shortage of basic data in relation to actual use, which result in the frequent problem of the under-or over-design of water and hot water supply. The following study measures the hot water supplier's conditions and the user's heat usage to realize the amount of time required for hot water supply load generation and the pattern of actual use in order to create basic data for effective hot water supply facility design and maintenance.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.10a
• /
• pp.156-161
• /
• 2004

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar hot water heater with high efficiency has been used for the house and the industrial process on business, advanced nations were reached up the experimental stage of solar generation system. But, the actual circumstance of the domestic has been not accomplished the popularization of solar hot water heater and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar hot water heater, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar hot water heater, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid for the enlargement and the popularization on solar energy.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.260-264
• /
• 2003

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar-heat hot-water-boiler with high efficiency has been used for the house and the industrial process on business, advanced nations on reached up the experimental stage of solar generation system. But the actual circumstance of the domestic has been not accomplished the popularization of solar-heat hot-water-boiler and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar-heat hot-water-boiler, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar-heat hot-water-boiler, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid f3r the enlargement and the popularization on solar energy.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.2
• /
• pp.103-109
• /
• 2006

The Purpose of this work is to investigate a long-term thermal performance of active solar hot water heating system for the dormitory of university. For this, monitering system including temperature sensors, flow-meters was installed in this system. Measurement was continued for 13 months between April 1st 2004 and May 31th 2005. As results, hot water demand, daily and monthly hot water load distribution which are necessary for the solar system design were suggested. Also thermal stratification in solar buffer tank was observed in the point of increasement of system efficiency. The yearly solar fraction and system efficiency of this system are about 29.5% and 44.9% respectively.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.417-417
• /
• 2009

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar hot water heater with high efficiency has been used for the house and the industrial process on business, advanced nations were reached up the experimental stage of solar generation system. But, the actual circumstance of the domestic has been not accomplished the popularization of solar hot water heater and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar hot water heater, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar hot water heater, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid for the enlargement and the popularization on solar energy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.28 no.9
• /
• pp.355-360
• /
• 2016

Continuing to the modeling of heating load, this paper, as the second part of consecutive works, presents LS-SVM (least square support vector machine) based model of winter time apartment hot water supply load in a district heating system, so as to be used in prediction of heating energy usage. Similar, but more severely, to heating load, hot water supply load varies in highly nonlinear manner. Such nonlinearity makes analytical model of it hardly exist in the literatures. LS-SVM is known as a good modeling tool for the system, especially for the nonlinear system depended by many independent factors. We collect 26,208 data of hot water supply load over a 13-week period in winter time, from 12 heat exchangers in seven different apartments. Then part of the collected data were used to construct LS-SVM based model and the rest of those were used to test the formed model accuracy. In modeling, we first constructed the model of district heating system's hot water supply load, using the unit heating area's hot water supply load of seven apartments. Such model will be used to estimate the total hot water supply load of which the district heating system needs to provide. Then the individual apartment hot water supply load model is also formed, which can be used to predict and to control the energy consumption of the individual apartment. The results obtained show that the total hot water supply load, which will be provided by the district heating system in winter time, can be predicted within 10% in MAPE (mean absolute percentage error). Also the individual apartment models can predict the individual apartment energy consumption for hot water supply load within 10% ~ 20% in MAPE.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.3
• /
• pp.45-54
• /
• 2007

For a conventional natural-circulation type solar water heater, the pressure head is limited by the height between the storage tank and hot water tap. Therefore, it is difficult to provide sufficient hot water flow rate for general usage. This study deals with a design modification of the storage tank to utilize the tap-water pressure to increase hot-water supply Based on fluid dynamic and heat transfer theories, a series of modeling and simulation is conducted to achieve practical design requirements. An experimental setup is built and tested and the results are compared with theoretical simulation model. The storage tank capacity is 240 l and the outer diameter of piping was 15 mm. Number of tube turns tested are 5, 10, and 15. Starting with initial storage tank temperature of $80^{\circ}C$, the temperature variation of the supply hot water is investigated against time, while maintaining minimum flow rate of 10 1/min. Typical results show that the hot water supply of minimum $30^{\circ}C$ can be maintained for 34 min with tap-water supply pressure of 2.5 atm, The relative errors between modeling and experiments coincide well within 10% in most cases.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.5
• /
• pp.25-30
• /
• 2010

The authors have studied on the corrosion resistance of the hot stamped steel sheets for the application to automotive parts. Recently automotive companies have focused on the hot stamped parts to meet the light weighting needs and the safe reason. Because of the cost reduction of the hot stamped parts, automotive companies increase the usage of the coated steel sheets, especially Al-Si coated steel sheets. The coated layer of Al-Si coated steel sheets contains up to 50% of Fe, which was diffused from the steel sheet, after hot stamping. The hot stamped steel sheet was not phosphated due to the oxidation layer of the coating, however, the result of the water resistance test is similar to that of the conventional GA steel sheets. The pitting depth and the weight reduction of the coated layer of hot stamped steel sheets are less than those of GA steel.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.6
• /
• pp.517-525
• /
• 1984

This paper presents a typical solar domestic hot water system and estimates their performances with variance of collector size, storage volume, collector tilt and other factors. The analysis is performed by th computer simulation for which conceptual system against 8760 hourly solar intensities and ambient temperature for a model year stored in the computer has been running. System performance is analyzed on hourly, monthly and yearly basis respectively and at the same time, the economics of various systems are evaluated. And also, this paper shows how an optimized design can be selected for any locality for which solar data and collector performance are provided. The results of this study are as follows. (1)Storage volume of 45 liter per square meter of solar collector lead to the best design. (2)Tilting the collectors to the same angle of the latitude is generally the best (3)Optimal size of collector is approximately 6.68-8.35m$^{2}$ when the latitude is 37.6 .deg. N and storage volume is 300 liter. (4)The performances of a solar domestic hot water system does not depend on the hourly usage but the daily usage.