• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.7
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• pp.630-638
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• 2004

Liquid desiccant dehumidification systems have the ability to provide efficient humidity and temperature control while saving the electrical energy requirement for air conditioning as compared to a conventional system. The dehumidifier and the regenerator form the heart of this system. The latent part of the cooling load is overcome using liquid desiccant. The model regenerator has been designed to study the absorption characteristic of the aqueous triethylene glycol (TEG) solution which is in the flow range from 20 to 50 LPM. Also, this system designed that was able to change the height of the regenerator and dehumidifier. Because the effect of performance have different result according the height. The effect of performance factors of the regenerator with inlet solution flow rate, air flow rate, solution concentration, solution temperature, brine temperature, air temperature and inlet air relative humidity have been analyzed. Data obtained are useful for design guidance and performance analysis of the hybrid air conditioning system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.4
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• pp.359-369
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• 2006

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. This system is applied with $k-{\varepsilon}$ turbulent model and using incompressibility viscosity flow range and boundary condition which are related to Bossinesq approximation following density variation in control volume. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.99-104
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• 2006

Accurate flow rate distribution has been become a very important part for controling of air change rate since the introduction of house ventilation system. An inappropriate selection of fan due to Incorrect prediction of friction loss makes waste energy. The purpose of this study is to recognize applicability of T-Method at house ventilation system by comparing experiment with T-method, The result of this study is as follows Flow rate is small amount in a house, so duct size must be accurate. And duct design with Equal Friction Loss Method presented large error range. Equal friction loss method is not fit to applicate small amount air flow rate. T-Method predicts accurate flow rate comparatively in a house ventilation system. Error range was 3.5%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.8
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• pp.433-438
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• 2009

Experimental results for performance characteristics of small $NH_3$ absorption chiller/ heater are presented. The apparatus consists of 7RT water-cooled absorption system, solution pump, boiler, cooling tower and peripheral devices. The effect of experimental parameters, such as refrigerant mass flow rate, solution mass flow rate and cooling water temperature have been investigated in view of the system performance. The capacity of each heat exchanger increased as refrigerant mass flow rate increased in cooling mode. Also, a cooling capacity increased as a strong solution mass flow rate increased. The cooling and heating COP show 0.5, 1.5 regardless of refrigerant mass flow rate, respectively. The results focus on the evaluation for performance characteristics of system with respect to variation of refrigerant mass flow rate under standard design conditions.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.9-17
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• 2002

This analysis is aimed to find out how the conditions of secondary air injection affects the residence time and the turbulence energy of flue gas and flow field in a small incinerator. A commercial code, PHOENICS, is used to simulate the flow field of an Incinerator. The computational grid system is constructed in a cartesian coordinate system In this numerical experiment, an independent numerical variable is the conditions of secondary air injection and dependants are the residence time of flue gas and the mean value of turbulence energy in a primary combustion chamber. The flow field and the distribution of turbulence energy are analysed to evaluate the residence time of flue gas and the turbulence energy The computational results say that the tangential injection of secondary air make the residence time much longer than the radial injection and that the radial injection of secondary make turbulence much stronger than the tangential injection.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1137-1143
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• 2006

The purpose of this research lays on examining the adequacy of the hybrid ventilation system. The hybrid ventilation system must satisfy the next to be used. Firstly, the cold-draft phenomenon must not exist in the occupied zone. Secondly, the condensation must not happen on the surfaces of vents. Thirdly, the flow of make-up air must be happened in an each space by exhausted air of a rest room and living room. We used an examination and CFD method to verify these. Trough the examination of air-vents, We confirmed that the cold-draft to be induced by make-up air does not happen and could not find the condensation in the limits of outdoor temperature higher than 265K. Through CFD simulation, We confirmed that the rapid temperature change existed only within 0.5m the occupied zone and the flow of air was happened in an each space by only exhausted air in the rest room and living room. Consequently, the hybrid system is possible method to an apartment house.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.429-439
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• 2003

Counter-current two-phase flows of air- water in narrow rectangular channels with offset strip fins have been experimentally investigated in a 760 mm long and 100 mm wide test section with 3.0 and 5.0 mm gap widths. The two-phase flow regime, channel-average void fractions and two-phase pressure gradients were studied. Flow regime transition occurred at lower superficial velocities of air than in the channels without fins. In the bubbly and slug flow regimes, elongated bubbles rose along the subchannel formed by fins without lateral movement. The critical void fraction for the bubbly-to-slug transition was about 0.14 for the 3 mm gap channel and 0.2 for the 5 mm gap channel. respectively. Channel-average void fractions in the channels with fins were almost the same as those in the channels without fins. Void fractions increased as the gap width increased, especially at high superficial velocity of air. The presence of fins enhanced the two-phase distribution parameter significantly in the slug flow, where the effect of gap width was almost negligible. Superficial velocity of air dominated the two-phase pressure gradients. Liquid superficial velocity and channel gap width has only a minor effect on the pressure gradients.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.9
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• pp.610-619
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• 2011

This paper investigates the simplified comfort index and control logic for VRF (Variable Refrigerant Flow) system by using 3 environmental factors such as temperature, humidity and air flow. Indoor test under thermal load was conducted to explore relationship of each environment factors that is related to simplified comfort index. Simplified comfort function that has 3 environmental variables was proposed based on survey results. Each factor is measured and comfort preference was surveyed by more than 30 subjects in the indoor comfort test. Moreover, control logic for VRF system was developed and then simulated by using thermal load calculation method and verified with test. The proposed comfort function was in good agreement with survey results, and also verification test trend of comfort change and maintenance are quite similar with survey. Furthermore, through the additional test data analysis some differences of comfort according to position of people staying in the test room were additionally investigated by air flow. People being under an exit of air in the indoor air-conditioner feel more comfortable condition and speed of response to comfort change is relatively fast.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.773-781
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• 2004

This research was Performed to raise grade efficiency of Sturtevant type air classifier. to treat powder less than $74\mu\textrm{m}$ particle produced at the crushing process of the dry aggregates manufacturing system or concrete wastes recycling system. The experimental conditions were in the ranges. 0.85 to 5.15 $m^3$/s of primary air flow rate. 0.005 to 0.015 $m^3$/s of secondary air flow rate $30^{\circ}$ to $70^{\circ}$ of auxiliary blades angle. respectively. for 1.7~3.3 kg/min of the powder feed rate. It was found that the grade efficiency of the air classifier was increased as the baffle plate was attached at the expansion region. and the optimal operating conditions of the air flow rates and the blade angle were obtained. The fractional recovery curves from the experiments were well agreement with the theoretical one of Molerus model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.2
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• pp.120-130
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• 2000

A flow uniformity in a duct cooler of duct system of FGD(Flue Gas Desulfurization) linking a reheater and a absorber has been investigated in the present study. For this purpose, the flow characteristics according to the geometry of a vertical and horizontal vane in a curved duct of the duct system has been examined with the aid of a numerical simulation. The results indicate that the vertical vane with a little deflection toward a recirculation region makes the flow distribution in the duct cooler more uniform than that without deflection, and horizontal vane does not effect the change of the flow distribution for an angle of inclination. The mean flow uniform factor shows its maximum for duct system without the vane(case NP) and its minimum for the vertical vane with a little deflection(case P-0.8-0) .