• Journal of the Korean Solar Energy Society
• /
• v.34 no.3
• /
• pp.49-56
• /
• 2014

A fiat-plate or vacuum tube solar collector have been mainly used for hot water supply of house because of some being difficult to get uniform energy density, so little applied into industrial field. This study is to apply the PTC(parabolic trough collector) solar collector into industrial field such as sludge dewatering system for energy reduction. The real scale system which composed of PTC Solar Collector and Thermal Dewatering (TDW) is established. PTC solar collector is designed to produce a hot water with $80^{\circ}C$ of temperature. And size of TDW is $630{\times}630mm$. Hot water produced from PTC solar collector is supplied into heating plate of TDW, and sludge like waterworks or wastewater is dewatered. PTC solar collector with $10m^2$ of area produce energy of average 5,618 kcal. As according to results from real scale performance, solar collector takes charge 94 % of the amount that TDW consume energy which is so large part if compare with boiler. It means that PTC solar collector is useful to apply industrial field under the condition of sufficient solar radiation. And it is analyzed that TDW by PTC solar collector has an economical validity.

• Journal of Bio-Environment Control
• /
• v.5 no.1
• /
• pp.57-64
• /
• 1996

To use effectively the solar energy in greenhouse heating, a high performance solar collector should be developed. And then the size of the solar collector and thermal storage tank should be determined through the calculation of heating load. The solar collector must be set in the optimum tilt angle and direction to take daily solar radiation maximally, and the flow rate of heat transfer fluid through the solar collector should be kept in the optimum range. In this research, the performance tests of a capillary tube solar collector were performed to determine the optimum water flow rate and the results summarized as follows. 1. The regressive equations for efficiency estimations of the capillary tube solar collector in the open loop were modeled in the water flow rate of 700-l,000 $\ell$/hr. 2. The optimum water flow rate of the solar collector was estimated by the second order polynomial regression and the maximum efficiency was 80% at the water flow rate of 850 $\ell$/hr. 3. The solar thermal storage system consisted of a capillary tube solar collector and a water storage tank was tested at the water flow rate of 850 $\ell$/hr in the closed loop, and obtained the solar thermal storage efficiency of 55.2%. 4. As the capillary tube solar collector engaged in this experiment was made of non-corrosive polyolefin tubes, its weight was as light as 1/30 of the flat plate solar collector made of copper tubes. Therefore it was considered to be suitable for the greenhouse heating system.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.32 no.E
• /
• pp.74-79
• /
• 1990

Important factors in evaluating solar collcetor efficiency are solar radiation, temperature and flow rate of the working fluid. The effects of these factors on the energy and the exergy gained by water, the working fluid, from the collector were analyzed. The results indicated that the collector efficiency and the energy and the exergy gained by the water from the collcetor increased with the increase of solar radiation. According to the exergy analysis, as the water temperature at the inlet of the collector increased, the exergy gained by the water increased while the energy gained by the water decreased. The water temperature at the outlet of the collector could be calculated with a mean error of 2.8%, and the energy and the exergy could be calculated theoretically with mean errors of 16.8% and 19.1%, respcetively.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.2
• /
• pp.19-27
• /
• 2012

This paper describes an experimental study on efficiency of solar collector in solar water heating system connected to hourly water heating load. In general, the functional form of solar efficiency is expressed as a function of fluid temperature entering solar collector, ambient temperature, and solar irradiance. When energy saving from solar heating of water heating system is analyzed on along-term basis such as one year with given solar irradiance data, simplified analysis is more convenient han detailed system simulation for quick assessment. However, the functional form of the efficiency is not convenient for approximately simplified energy analysis because the inlet temperature can be obtained through a detailed system simulation. In the study, solar collector efficiency is obtained with various daily water heating load sand daily solar irradiance using experimental tests. The study also considers large residential buildings such as apartment buildings for application of solar water heating systems. From test results, it is found that daily solar collector efficiency is proportional to daily water heating loads and daily solar irradiance. The data obtained from the study can be utilized to find a functional relation between daily solar irradiance and daily heating load in stead of collector inlet temperature for application of solar collector efficiency to long-term approximated energy analysis of solar heating system.

• Solar Energy
• /
• v.6 no.1
• /
• pp.47-59
• /
• 1986

This paper presents the establishment of optimum design conditions and economic evaluation for solar hot water system. The aim of this study is to present thermal performance of solar heating systems and to determine their performance as a function of collector size, storage capacity, tilting of collector and other factors. By analyzing its performance under the various conditions, optimum design of solar heating system can be obtained. System performance are obtained monthly and yearly basis respectively. At the same time the economics of various systems are evaluated. For the computer simulation Mokpo, Kangnung, Chupungnyong and Seoul are selected for particular installation places. As a result, the optimal design condition of solar heating system considering the following factors such as installation angle of collector, capacity of storage tank, collector size in each place can be obtained as follows; (1) Installation angle of collector Tilt = lattitude (2) Capacity of storage tank Solar domestic hot water system : $45\;1/m^2$ Multifamily solar domestic hot water system : $35\;1/m^2$ (3) Collector size i) Solar domestic hot water system Seoul & Chupyungyong area : $11.52\;m^2$ Mokpo area : $8.64\;m^2$ ii) Multifamily solar domestic hot water system Seoul, Chupyungyong & Mokpo area : $345.6\;m^2$ Kangnung area : $259.2\;m^2$

• Journal of the Korean Solar Energy Society
• /
• v.32 no.5
• /
• pp.11-17
• /
• 2012

In this study, a simulation program was developed with heat transfer model in the thermal storage tank for a solar collector and burner combined heating and hot water supply system. Analysis was conducted with variation of operating condition and schedule to analyze performance of a hot water supply and panel heating system with a solar collector and burner combined thermal storage tank. The simulation program is divided two sections. One part is calculation of temperature variation of water which flows through the panel in the floor for heating of the residential house during 24 hours, and the other part is heat transfer calculation for the reaction time to get desired water temperature in the thermal storage tank. As results, light oil consumption and system performance during operation period were analyzed with variation of climate condition and with or without solar collector. Most of the case, oil could be saved about from 24 to 41% with installing the solar collector. The performance of the system is more dependent on radiation time of the solar collector rather than the intensity of the solar radiation which was adopted for the climate analysis.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.221-225
• /
• 2009

A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat. A flat plate is the most common type of solar thermal collector, and is usually used as a solar hot water panel to generate solar hot water. A flat plate collector consists basically of an insulated metal box with a glass or a plastic cover and a dark-colored copper absorber plate. Solar radiation is absorbed by the copper absorber plate and transferred to water that circulates through the collector in copper tubes. Ultrasonic welding is an industrial technique whereby high-frequency ultrasonic acoustic vibrations are locally applied to work pieces being held together under pressure to create a solid-state weld. In this study, we developed solar collector ultrasonic welding machine with digital controlled power supply and tested various welding conditions such as welding pressure, welding amplitude, welding speed. Welding speed was considered in 2~12m/min. The width of ultrasonic welds was increased with welding amplitude by 2.2~2.5mm. The fracture load of ultrasonic welds showed 20% higher than domestic products.

• Journal of the Korean Solar Energy Society
• /
• v.36 no.4
• /
• pp.49-56
• /
• 2016

The objective of this work is to analyze the variation in energy performance for each flat plate collector connected in series. In this study, it was assumed that solar water heating system with annual solar fraction of 60% was installed in an office building in Seoul, South Korea. The transient energy performance corresponding to four cases, which are selected using different solar radiation and outdoor air temperature, is studied by analyzing the variation in outlet temperature, solar useful heat gain, and thermal efficiency of each collector. It is observed that the useful heat gain and the collector efficiency decrease continuously, and outlet temperature increases when increasing the number of collector connected in series. The long-term performance is assessed by evaluating the thermal efficiency of each collector for two solar radiation conditions ranging from 780 to $820W/m^2$ and from 380 to $420W/m^2$. It is found that the differences between the intercept and slope of the efficiency curves for first and eighth collectors are 3.68% and 6.74% for solar radiation of $800{\pm}20W/m^2$ and 8.57% and 12.90% for solar radiation of $400{\pm}20W/m^2$, respectively. In addition, it is interesting to note that annual useful heat gain and collector efficiency are reduced with similar rate of about 6.13% when increasing the collector area by connecting the collectors in series.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.4
• /
• pp.167-173
• /
• 2007

This study analyzed by simulation using TRNSYS as well as by experiment on the solar district heating system installed for the first time for the district heating system in Bundang. Simulation analysis using TRNSYS focused on the thermal behavior and long-term thermal efficiency of solar system. Experiment carried out for the reliability of simulation system. This solar system where the circuits of two different collectors, flat plate and vacuum tube collector, are connected in series by a collector heat exchanger, and the collection characteristics of each circuit varies. Therefore, these differences must be considered for the system's control. This system uses variable flow rate control in order to obtain always setting temperature of hot water by solar system. Specifically, this is a system that heats returning district heating water (DHW) at approximately $60^{\circ}C$ using a solar collector without a storage tank, up to the setting temperature of approximately $85{\sim}95^{\circ}C$ To realize this, a flat plate collector and a vacuum tube collector are used as separate collector loops. The first heating is performed by a flat plate collector loop and the second by a vacuum tube collector loop. In a gross collector area basis, the mean system efficiency, for 4 years, of a flat plate collector is 33.4% and a vacuum tube collector is 41.2%. The yearly total collection energy is 2,342GJ and really collection energy per unit area ($m^2$) is 1.92GJ and 2.37GJ respectively for the flat plate vacuum tube collector. This result is very important on the share of each collector area in this type of solar district heating system.

• KIEAE Journal
• /
• v.16 no.6
• /
• pp.167-172
• /
• 2016

Purpose: The solar water heater with natural circulation has been used for several decades in the world as it is automatically operated without a pump and controller and is easy to maintain and repair. After the subsidy was offered from 2012, the solar water heater with natural circulation is becoming increasingly popular in Korea. Recently, the development of a wall-integrated solar water heater, which improves the applicability of buildings and prevents the overheating in the summer, is being developed. On the other hand, the design and performance evaluation data of solar water heaters are very inadequate, and analysis of heat and flow is required to develop a new type of solar water heater. Method: Therefore, in this study, we proposed a new simplified system analysis model that reflects heat and pressure loss from the test results of KS B ISO 9806-1 (Solar collector test method), assuming that the collector is a simple pipe system, the validity of which was verified through experiments. Result: As a result, first, the RMSE of the system circulation flow rate and the average temperature of the inlet and outlet of the collector according to the experimental results and the simulation are 0.05563 and 0.88530, respectively, which are very consistent. Secondly, the mass flow rate is increased linearly with the increase of the solar radiation, and the mass flow rate is 0.0104 ~ 0.0180kg/s in the range of $200{\sim}380W/m^2$ of solar irradiance. Compared with the test flow rate 0.0764kg / s of the test collector, it showed a level of less than 20%.