Performance Study of an Oil-Immersed Power Transformer With Shallow Geothermal Cooling

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Gerd Schmid ◽  
Chien-Yeh Hsu ◽  
Yu-Ting Chen ◽  
Tai-Her Yang ◽  
Sih-Li Chen
Keyword(s):  
Experimental Data ◽  
Thermal Analysis ◽  
Heat Exchanger ◽  
Water Flow ◽  
Cooling System ◽  
Flow Direction ◽  
Water Flow Rate ◽  
Transformer Oil ◽  
Performance Study ◽  
Cooling Performance

This paper investigates the cooling performance of a shallow geothermal energy method in relation to the cooling system of a 75 kVA oil-immersed transformer. A thermal analysis of the complete system is presented and then validated with experimental data. The cooling performance of the shallow geothermal cooling method is indicated by its cooling capacity and average oil temperature. The results of this study show that the average oil temperature can be reduced by nearly 30 °C with the aid of an 8 m deep U-pipe borehole heat exchanger, thereby making it possible to increase the capacity of the transformer. By increasing the water flow rate from 6 L/m to 15 L/m, the average oil temperature could be lowered by 3 °C. In addition, the effects of changing the circulating water flow direction and the activation time of the shallow geothermal cooling system were investigated. The results of the thermal analysis are consistent with the experimental data, with relative errors below 8%. The results of the study confirm that a larger temperature difference between the cooling water and the transformer oil at the inlet of the heat exchanger can increase the overall heat transfer rate and enhance the cooling performance of the shallow geothermal cooling system.

Experimental Study on the Avoidance and Suppression Criteria for the Vortex-Induced Vibration of a Cantilever Cylinder

2002 ◽  
Vol 124 (2) ◽  
pp. 187-195 ◽  
Author(s):  
Takaaki Sakai ◽  
Masaki Morishita ◽  
Koji Iwata ◽  
Seiji Kitamura
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Water Flow ◽  
Experimental Validation ◽  
Flow Direction ◽  
High Viscosity ◽  
Design Guideline ◽  
Vortex Induced Vibration ◽  
High Viscosity Oil ◽  
Effect Of Structure

Experimental validation of the design guideline to prevent the failure of a thermometer well by vortex-induced vibration is presented, clarifying the effect of structure damping on displacement amplitudes of a cantilever cylinder. The available experimental data in piping are limited to those with small damping in water flow, because of the difficulty in increasing structure damping of the cantilever cylinders in experiments. In the present experiment, high-viscosity oil within cylinders is used to control their structure damping. Resulting values of reduced damping Cn are 0.49, 0.96, 1.23, 1.98, and 2.22. The tip displacements of the cylinder induced by vortex vibration were measured in the range of reduced velocity Vr from 0.7 to 5 (Reynolds number is 7.8×104 at Vr=1). Cylinders with reduced damping 0.49 and 0.96 showed vortex-induced vibration in the flow direction in the Vr>1 region. However, in cases of reduced damping of 1.23, 1.98, and 2.22, the vibration was suppressed to less than 1 percent diameter. It is confirmed that the criteria of “Vr<3.3 and Cn>1.2” for the prevention of vortex-induced vibration is reasonably applicable to a cantilever cylinder in a water flow pipe.

Estimation of Optimal Water Flow Rate of a Steel Roller Shutter with Water Film Cooling System

2014 ◽  
Vol 905 ◽  
pp. 263-267
Author(s):  
Shin Ku Lee ◽  
W.H. Lo ◽  
M.C. Ho ◽  
T.H. Lin
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Inverse Method ◽  
Cooling System ◽  
Water Flow Rate ◽  
Water Film ◽  
Steel Roller ◽  
Fire Environment ◽  
Hot Surface

The hybrid inverse method to estimate the optimal water flow rate and surface temperature on the hot surface of the steel roller shutter with water film cooling system subjected to a fire environment is presented in this paper. The results show that the effect of the down-flowing water film flow rate on the present estimates cannot be negligible. The water-film system combined with the steel roller shutter can effectively improve the heat resistance and the temperature of the shutter slat surface can be controlled to around 100 °C. The optimal water flow rate is 110 L/min for a typical 3m x 3m steel roller shutter with water film cooling system.

Correlation Investigation of Condensation Heat Exchanger Design for Secondary Passive Cooling System

2012 ◽  
Author(s):  
Hee Joon Lee ◽  
Han-Ok Kang ◽  
Tae-Ho Lee ◽  
Cheon-Tae Park
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Cooling System ◽  
Condensation Heat Transfer ◽  
Passive Cooling ◽  
Heat Transfer Correlation ◽  
Data Set ◽  
Heat Exchanger Design ◽  
Passive Cooling System

Recently vertical or horizontal type condensation heat exchangers are being studied for the application to secondary passive cooling system of nuclear plants. To design vertical condensation heat exchanger in water pool, a thermal sizing program of condensation heat exchanger, TSCON (Thermal Sizing of CONdenser) was developed in KAERI (Korea Atomic Energy Research Institute). In this study, condensation heat transfer correlation of TSCON is evaluated with the existing experimental data set to design condensation heat exchanger without non-condensable gas (pure steam condensation). From the investigation of the existing condensation heat transfer correlation to the existing experimental data, the improved Shah correlation showed most satisfactory results for the heat transfer coefficient and mass flow rate in a heat exchanger in both subcooled and saturated water pools without the presence of non-condensable gas.

Performance Study of a Dimpled-Protruded Air-to-Air Plate Heat Exchanger

2015 ◽  
Author(s):  
Amro M. Alqutub ◽  
Majid T. Linjawi ◽  
Ismail M. Alrawi
Keyword(s):  
Reynolds Number ◽  
Heat Exchanger ◽  
Flow Direction ◽  
Plate Heat Exchanger ◽  
Performance Study ◽  
Maximum Heat ◽  
Plate Heat ◽  
Structural Support ◽  
Two Fluids ◽  
Aluminum Plates

In the present study, the overall heat transfer coefficient, friction factors, and effectiveness of a dimple-protrusion air-to-air counter-flow plate heat exchanger have been measured at low Reynolds number (500 < Re < 4,000). The heat exchanger consists of 4 channels per flow direction built using 1 mm aluminum plates. Dimples are specially arranged such that protrusions are opposed for applications that require structural support to withstand high pressure difference between the two fluids. A maximum heat enhancement level of 3.2 was obtained with a penalty of increased friction factor by 9 times which leads to a maximum performance factor of 1.5. The effectiveness obtained was found to be almost independent of Reynolds number on most tested Re. A detailed uncertainty analysis has been performed to determine the uncertainty in the results.

scholarly journals Experimental Study on the Heat Transfer Characteristics of the Enhanced Fin-Tube Heat Exchanger Applied a Coiled Turbulator

2017 ◽  
Author(s):  
Sun-Joon Byun ◽  
Sang-Jae Lee ◽  
Jae-Min Cha ◽  
Zhen-Huan Wang ◽  
Young-Chul Kwon
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Water Flow ◽  
Flow Rate ◽  
Heat Transfer Performance ◽  
Water Flow Rate ◽  
Transfer Performance ◽  
Tube Heat Exchanger ◽  
Fin Tube

This study presents the comparison of heat transfer capacity and pressure drop characteristics between a basic fin-tube heat exchanger and a modified heat exchanger with the structural change of branch tubes and coiled turbulators. All experiments were carried out using an air-enthalpy type calorimeter based on the method described in ASHRAE standards, under heat exchanger experimental conditions. 14 different kinds of heat exchangers were used for the experiment. Cooling and heating capacities of the turbulator heat exchanger were excellent, compared to the basic one. As the insertion ratio of the coiled turbulator and the number of row increased, the heat transfer performance increased. However, the capacity per unit area was more effective in 4 rows than 6 rows, and the cooling performance of the 6 row turbulator heat exchanger (100% turbulator insert ratio) was down to about 6% than that of 4 row one. As the water flow rate and the turbulator insertion ratio increased, the pressure drop of the water side increased. This trend was more pronounced in 6 rows. In the cooling condition, the pressure drop on the air side was slightly increased due to the generation of condensed water, but was insignificant under the heating condition. The power consumption of the pump was more affected by the water flow rate than the coiled turbulator. The equivalent hydraulic diameter of a tube by the turbulator was reduced and then the heat transfer performance was improved. Thus, the tube diameter was smaller, the heat flux was better.

Using a Multiport Pitot Tube in Circulating Water Flow Measurements

2007 ◽  
Author(s):  
Luis R. Figueroa Ibarra ◽  
J. Hugo Rodri´guez Marti´nez ◽  
Marcelino Santaba´rbara Botello
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Thermal Power ◽  
Water Flow Rate ◽  
Pitot Tube ◽  
Flow Measurements ◽  
Circulating Water ◽  
Measurement Results ◽  
Made In

This paper details the design of a Pitot tube used for water flow rate measurements in large pipes. The paper describes first the nowadays commonly used device (simplex pitot), based on standard CTI Code ATC-105 from Cooling Tower Institute [1]. The disadvantages of the simplex pitot are pointed out, and the detailed description of the proposed device (multiport pitot) is explained. The Multiport Pitot, which design is also based on norm ATC-105, is able to perform real-time measurements. The paper also includes the results obtained from the water flow rate measurements made in the cooling system of a thermal power plant in Mexico. These measurement results were compared to simulation results obtained with a computational commercial simulation tool.

scholarly journals Controlling the Distribution of Cold Water in Air Cooling Systems of Underground Mines

2016 ◽  
Vol 61 (4) ◽  
pp. 793-807 ◽  
Author(s):  
Nikodem Szlązak ◽  
Dariusz Obracaj ◽  
Justyna Swolkień ◽  
Kazimierz Piergies
Keyword(s):  
Automatic Control ◽  
Water Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Cooling System ◽  
Water Flow Rate ◽  
Underground Mines ◽  
Air Cooling ◽  
Cooling Systems ◽  
Pipeline Network

Abstract In Polish underground mines in which excavations are subjected to high heat load, central and group cooling systems based on indirect cooling units are implemented. Chilled water, referred to as cold water and produced in chillers, is distributed through a pipeline network to air coolers located in mining and development districts. The coolers are often moved to other locations and the pipeline network undergoes constant modification. In such a system, parameters of cold water in different branches of the pipeline network need to be controlled. The article presents the principles for controlling the cooling capacity of air coolers installed in an underground mine. Also, the authors propose automatic control of water flow rate in underground pipeline network and in particular coolers, depending on the temporary cooling load in the system. The principles of such a system, controlling cold water distribution, and the functions of its individual components are described. Finally, an example of an automatic control of water flow rate in a central cooling system currently implemented in a mine is presented.

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