Chang-Dae Park

Development of Seawater Distiller utilizing Waste Heat of Portable Electric Generators

A seawater distiller, in which the waste heat from a portable electric generator was used, with a multiple-effect diffusion still was designed. The waste gas from small generators commonly used in islands has not yet been used because it has less thermal energy; however, this waste gas can be used as a heat source for small-capacity distillers and as an additional heat source for solar stills. The proposed distiller comprises a series of closely spaced parallel partitions that are placed in contact with saline-soaked wicks. In the distiller, evaporation and condensation processes are repeated to recycle the thermal energy for increasing the distillate productivity. Experimental results show that the proposed distiller with only one-effect still can produce at least 6.7 kg/day of distilled water; the proposed distiller with a ten-effect still is expected to produce 43 kg/day of distilled water. This amount of distillate is approximately four times the maximum daily productivity of the solar stills, as determined in outdoor experiments.

Experiment for attaching performance of a fan and vacuum pad on grooved vertical concrete walls

In order to measure attaching performance of the fan and vacuum pad from concrete wall surface, test apparatuses measuring suction force of them were developed. Using these test apparatuses, four types of concrete wall specimens were tested to measure the attaching force. The test apparatuses consisted of a pneumatic cylinder, a load cell, and sensors for vacuum pressure. Surface samples with concrete material were manufactured as four different shapes that is flat, step, rib, and embossing type. Then, attaching forces of the fan and vacuum pad were measured as changing specimen types and the vacuum pressure of the pad, and the rotation speed of the fan. In case of the fan, test result shows that the suction force is proportional to the fan speed, and interestingly, the suction force is almost independent of the specimen shapes. In case of the vacuum pad, the attaching force is almost steady though varying vacuum pressure excepting flat surface. The vacuum pad might be more affected than the fan according to surface shapes.

Parametric performance test of distiller utilizing solar and waste heat

AbstractA seawater distiller utilizing the thermal energy of solar radiation and waste gas from a small electric generator was designed and constructed with a number of configurations to improve its performance. The distiller constructed is a combined model of a basin-type solar still and a vertical multiple-effect diffusion still, consisting of a series of closely spaced parallel plates in contact with saline-soaked wicks. Evaporation and condensation processes were repeated on all the plates by recycling thermal energy to increase distillate productivity in the still. Tests were performed with waste heat of actual exhaust gas from a portable electric generator, changing various experimental conditions such as feeding flow rate of seawater to the wicks, seawater level of the basin, and use of reflecting plate fins. Experimental results show that our two-effect distiller produces 17.1–19.6 kg/(m2 d) at 3,000 kJ/h and has a Performance Ratio of 14.8–16.9.

Measurement of Vacuum Suction Force on Diversely Configured Vertical Outer Walls of Buildings

Though vacuum suction pads are able to fasten items of working equipment such as gondolas easily and without causing damage to a building’s outer wall, their necessary suction force should be designed by considering various conditions such as wind force, the loads of each item of working equipment, and suction capacity. Suction force is changed by the internal vacuum pressure of pads, and the materials and shapes of an outer wall’s surface have a considerable influence on vacuum pressure. In this study, we measured the vacuum suction force of pads on walls configured of various materials and shapes.

Performance and Availability of Seawater Distiller with Heat Pipe Utilizing Low-Grade Waste Heat

Exhaust gas from a small portable electric generator is simply exhausted to the surroundings because the capacity and quality of the waste heat of this gas is generally not sufficient to recover and utilize. We have proposed a seawater distiller utilizing the thermal energy of waste gas from an electric generator. The distiller recovers heat from the waste gas by means of a heat pipe and uses it effectively through a multiple-effect diffusion-type structure. We constructed an experimental apparatus with a vertical single-effect still having a 4-stroke 50 cc generator engine and found that the experimental results for distillate productivity show good agreement with the theoretical predictions. The results show that the distiller can recover 52 W of waste heat from the gas at , and ~85% of the recovered heat can be utilized for distillation to produce 70 g/h of fresh water. This is equivalent to a productivity of 500 g/h in the case of a 10-effect still. Therefore, the proposed distiller should be useful in remote areas where electricity and water grids are inadequate.

Procedure and Method of Equipment Qualification for Solenoid-Operated Valves Used in Nuclear Power Plants

Key Words: Solenoid Operated Valve(솔레노이드밸브), Equipment Qualification(기기검증), Power Operated Valve(동력구동밸브), Nuclear Power Plant(원자력발전소)초록: 원자력발전소용솔레노이드밸브의국산화에필수과정인기기검증기술을개발하기위해관련규정을분석하고, 시험절차및방법, 시험조건, 시험장치및허용기준등을구체화하였다. 솔레노이드밸브의기기검증규격은법규, 가이드, 규정등의순으로계층화되어있으며, 시험기기와시험항목에따라규정이세분화되어있다. 세부규정인IEEE를분석한결과기기검증시험은크게기능시험, 일반환경시험및사고시험으로구분되어있는데, 일반환경시험과사고시험을통해발전소환경과동일한조건에서솔레노이드밸브를노화시킨후기능시험에서노화된밸브의성능을확인하는방식으로검증시험을수행하도록구성되어있었다. 본논문에서제시한솔레노이드밸브의기기검증시험절차와방법은기기검증수행자뿐만아니라밸브제조사에게매우유용한기술자료가될것으로판단된다.Abstract: In order to develop technology for an equipment qualification (EQ) test, which is an importantprocess in localizing solenoid-operated valves used in nuclear power plants, we analyzed related regulations,test procedures, conditions, equipment, and acceptance criteria. EQ regulations for the solenoid-operated valveare classified as law, guide, and standard, and are subdivided according to test specimens and contents. TheEQ test is composed of functional, normal-, and accident- condition tests. The solenoid-operated valve is agedunder normal and accident conditions, which are predicted in the design conditions of a nuclear power plant,and the performance of the valve is measured by a functional test. The test method and procedure analyzedin this paper might be very useful for manufacturers as well as EQ testers.

Basic Experiment for a Fastening Device for the Vertical Outer Walls of High-Rise Buildings

In order to perform maintenance on the outer walls of a high-rise building, including sweeping, painting and repairs, a device that enables the easy attachment/detachment of working equipment such as a gondola to the outer wall of a building is necessary. Though vacuum suction pads can be used to fasten equipment to a vertical wall easily and without causing damage to the contact surface, their suction force should be designed by considering both external conditions and the loads of working equipment. In this study, we performed a basic experiment on the vacuum suction force of suction pads attached to a vertical wall under various load conditions.

Development of Load apparatus for Motor

We have constructed loading apparatuses to electrical motor with a powder brake and a oil pump for load test of a several ten kilowatt-motor and performed load test with two motors. On operating the loading apparatus with a oil pump, temperature of the oil may excessively increase and fail to operate due to dynamic energy loss of equipment in oil loop. In order to control the oil temperature, factors of the energy loss were analyzed and the quantitative loss was calculated. Load tests of motors with two loading apparatuses constructed were successfully performed and strengths of each apparatus come out on operating.