Gas cooling performance in disc winding of large-capacity gas-insulated transformer

IEEE Trans. Power Delivery

Li²

2006

Effects of various design and operating parameters on the hot-spot temperature are analyzed in disk-type forced oil-cooled transformer windings. The results indicate that a two-dimensional thermal analysis in the disks is necessary to determine the temperature and location of the hottest spot, and that the cooling oil-flow arrangement has a significant influence on the cooling of disk windings. The maximum disk temperature for each pass is proportional to the oil entrance temperature and, therefore, the heat transfer in the radiator should be improved as much as possible. A larger total oil-flow rate through the pass can increase the cooling capacity and, hence, improve the cooling of the disks, but increases the pressure loss. Although a uniform distribution of cooling oil flow among the various horizontal cooling ducts within a pass is beneficial to decrease the hottest spot temperature, the best cooling results can be obtained when the cooling flow distribution matches the distribution of heat generation in each disk of the pass.

Section: Effects Of Horizontal Duct Height and Vertical Duct Widthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oil Cooling for Disk-Type Transformer Windings—Part II: Parametric Studies of Design Parameters

IEEE Trans. Power Delivery

Li²

2006

“…Reverse flow can occur in the winding in an OD cooling mode, as indicated by the experimental work in [13] and the computational work in [21]. Once reverse flow occurs it can jeopardize the cooling performance because the reverse flow usually leads to a low flow rate and some horizontal cooling ducts may even suffer from stagnant flows.…”

Section: A Predicting the Occurrence Of Reverse Flow In A Passmentioning

confidence: 99%

“…In addition to CFD calibrations for the correlation equations, experiments were conducted to calibrate the Nusselt numbers in horizontal ducts [12]. Isothermal flow experiments were also conducted to determine the flow distribution and total pressure drop in a disc-type winding [13]. The influence of the number of discs per pass, ratio of horizontal duct height to vertical (axial) duct width and the effect of the elevation of the cooling system were investigated experimentally as well as via network modelling and CFD simulations using a finite difference method [13,14].…”

mentioning

confidence: 99%

Prediction of Pressure Drop and Flow Distribution in Disc-Type Transformer Windings in an OD Cooling Mode

IEEE Trans. Power Delivery

Wang

Liu

2017

In this paper, a method for predicting pressure drop and flow distribution in disc-type transformer windings in an oil forced and directed (OD) cooling mode is proposed. First, dimensional analyses are conducted to identify the independent dimensionless variables that affect pressure drop over and flow distribution in the winding. Next, parametric sweeps are performed with computational fluid dynamics (CFD) simulations under isothermal flow conditions. Finally, pressure drop and flow distribution results obtained from the simulations are correlated with the previously identified dimensionless variables to derive correlation equations. These equations have been verified over a range of different isothermal and non-isothermal flow cases and applied to identify the criteria for the occurrence of reverse flow resulting from a combination of pass inlet flow rate and winding geometry. In addition, the method provides an insight into the controlling parameters for determining the minimum oil velocity in horizontal cooling ducts.

“…For oil directed (OD) cooling modes, liquid flow and heat transfer are weakly coupled. Therefore, the hydraulic system and the thermal system can be investigated separately [3][4][5]. For oil forced/natural (OF/ON) cooling modes, liquid flow and heat transfer are strongly coupled and therefore buoyancy force and hot-streak dynamics play vital roles in determining the fluid flow and temperature distribution in the winding [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of influences of liquid types on flow distribution and temperature distribution in disc type ON cooled transformers

2017 IEEE 19th International Conference on Dielectric Liquids (ICDL)

Wang

Liu

et al. 2017

In this paper, dimensional analysis is adopted to study fluid flow distribution and temperature distribution in disc-type ON (oil natural) cooled transformer windings. Theoretical analysis on the thermal driving force and the pressure drop in the liquid circulation loop is also performed to determine the total liquid flow rate in the transformer. The thermal performance of three different liquids, a hydrocarbon mineral oil, a hydrocarbon gas-to-liquid (GTL) oil and a synthetic ester are investigated using computational fluid dynamics (CFD) simulations, based on the understanding from dimensional analysis and the flow rates determined from the theoretical analysis. It is found in the investigated conditions that the hydrocarbon mineral and GTL oil share similar thermal performance; the synthetic ester has a lower total flow rate due to its higher viscosity and therefore requires additional effort to improve the thermal performance.