Beijing Longyuan Cooling Technology Co.

Guodian, China

Beijing Longyuan Cooling Technology Co.

Guodian, China

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Du X.P.,Xi'an Jiaotong University | Zeng M.,Xi'an Jiaotong University | Dong Z.Y.,Beijing Longyuan Cooling Technology Co. | Wang Q.W.,Xi'an Jiaotong University
Experimental Thermal and Fluid Science | Year: 2014

An experimental system was built to study the heat transfer and resistance characteristics of two finned oval-tube heat exchangers (HE1: Double rows of tubes, HE2: Three rows of tubes.) inclined towards the air incoming flow direction. Four air inlet angles (90°, 60°, 45° and 30°) are investigated separately to acquire the heat transfer and pressure drop performances for Reynolds number ranging from 1300 to 13,000. The experimental correlations of Nusselt number and resistance coefficient of the air side are obtained, and the comprehensive comparisons of heat transfer performance are carried out. The results show that whether the heat transfer performance for heat exchangers positioned obliquely is improved or not is depended on not only their inclined angles, but also their structures. © 2013 Elsevier Inc.


Du X.,Xi'an Jiaotong University | Yin Y.,Xi'an Jiaotong University | Zeng M.,Xi'an Jiaotong University | Yu P.,Xi'an Jiaotong University | And 3 more authors.
Thermal Science | Year: 2014

A tremendous quantity of water can be saved if the air cooling system is used, comparing with the ordinary water-cooling technology. In this study, two kinds of finned tube heat exchangers in an indirect air-cooling tower are experimentally studied, which are a plain finned oval-tube heat exchanger and a wavy-finned flat-tube heat exchanger in a cross flow of air. Four different air inlet angles (90°, 60 °, 45°, and 30°) are tested separately to obtain the heat transfer and resistance performance. Then the air-side experimental correlations of the Nusselt number and friction factor are acquired. The comprehensive heat transfer performances for two finned tube heat exchangers under four air inlet angles are compared. For the plain finned oval-tube heat exchanger, the vertical angle (90°) has the worst performance while 45° and 30° has the best performance at small ReDcand at large ReDc, respectively. For the wavy-finned flat-tube heat exchanger, the worst performance occurred at 60°, while the best performance occurred at 45° and 90° at small ReDcand at large ReDc, respectively. From the comparative results, it can be found that the air inlet angle has completely different effects on the comprehensive heat transfer performance for the heat exchangers with different structures.


Li L.,Beijing Longyuan Cooling Technology Co. | Peng J.,Beijing Longyuan Cooling Technology Co. | Li H.,Beijing Longyuan Cooling Technology Co. | Yang Y.,China Academy of Building Research
Applied Mechanics and Materials | Year: 2013

Condensate pipe vibration in the air cooling system was analyzed. The flow pattern discrimination parameters were obtained through carrying out the iterative calculation on the continuity equation and flow equation. It was proposed to use the flow analysis method to determine pipe diameter and arrangement in the design, and to use the static and dynamic analysis methods to determine pipe support settings. These analysis methods are effective to actual engineering design proved by an example. Finally this paper puts forward the improvement measures to prevent condensate pipe vibration. © (2013) Trans Tech Publications, Switzerland.


Gang L.Z.,CAS Institute of Engineering Thermophysics | Lan H.X.,CAS Institute of Engineering Thermophysics | Wei T.D.,CAS Institute of Engineering Thermophysics | Yin W.Z.,CAS Shanghai Institute of Ceramics | Yi D.Z.,Beijing Longyuan Cooling Technology Co.
Advanced Materials Research | Year: 2012

A mathematical model is built for the heat and mass transfer during charge and discharge in a sodium sulfur cell by coupling the electrochemical equations with the equations of species transport and heat transfer. Numerical simulation is performed for the two-dimensional axisymmetric domain of a single cell. The simulated charge-discharge characteristics agree well with the experimental data of a 650 Ah Na/S cell. The transient non-uniform distributions of the electric potential, the current density, the sodium polysulfide composition and the temperature during charge and discharge are obtained. The results show that the non-uniform distribution of the sodium polysulfide composition and current density may deteriorate the degradation of the ceramic electrolyte and the corrosion of the metal container, thus may shorten the cell life. The graphite fibers in the sulfur electrode matrix are preferably radially oriented, which is advantageous for reducing the cell resistance, for improving the rechargeability and for extending the cell life. The simulation results of the transient temperature fields provide useful guidance for the optimized thermal design so as to enhance the energy efficiency of the battery system. © (2012) Trans Tech Publications, Switzerland.


Wang J.,Xi'an Jiaotong University | Zeng M.,Xi'an Jiaotong University | Wang Q.,Xi'an Jiaotong University | Dong Z.,Beijing Longyuan Cooling Technology Co.
Chemical Engineering Transactions | Year: 2011

The effects of different cooling delta angles on power plant natural draught dry cooling towers are investigated by means of Computational Fluid Dynamics (CFD) calculations. The heat exchangers are arranged horizontally in the inlet cross-section of the tower in the form of A-frames, which is also called cooling delta. A cooling delta consists of two cooling columns (heat exchanger tube banks), the angle between which is called cooling delta angle. This angle causes a non-uniform flow and temperature distribution within the heat exchangers, and thereby influences the thermal performance of the cooling tower. Since it is unpractical to model individual fins and tubes of a heat exchanger, the performance of the finned tube heat exchangers in the tower are modeled using a porous media approach, which is accurate enough instead of pore-scale simulations as long as the macroscopic properties are determined correctly. After a careful validation of the porous media approach, the 2D turbulent flow and pressure losses behind a cooling delta with different angles as well as the 3D natural convection heat transfer in natural draft dry cooling towers are studied. The results agree with the engineering reality and can be used to further find an optimal cooling delta angle for different projects. Copyright © 2011, AIDIC Servizi S.r.l.


Du X.,Xi'an Jiaotong University | Zeng M.,Xi'an Jiaotong University | Wang Q.,Xi'an Jiaotong University | Dong Z.,Beijing Longyuan Cooling Technology Co.
Chemical Engineering Transactions | Year: 2011

To save space, sometimes the heat exchanger is necessary to arranged obliquely. In view of the fact that the air entrance flow direction is not orthogonal to the heat exchanger surface in many cases for the direct and in-direct air cooling system, the present study describes the experimental system about the elliptical finned tube heat exchangers inclined towards the air oncoming flow. The inclined angles between the minor axis of the oval tube and the oncoming air flow are 90° and 60° separately. The heat transfer and pressure drop characteristics are investigated. The results show that the overall heat transfer coefficient of 60° is about 9.96 % smaller than that of 90° when the other conditions are the same, while the pressure drop has a significant change when the air velocity is big to some extent. At last the correlations of the convection heat transfer coefficient and resistant coefficient of the air side are acquired. And some conclusions are drawn upon the effects of the air entrance angles on the heat transfer and resistance performance of the elliptical finned tube heat exchanger. Copyright © 2011, AIDIC Servizi S.r.l.

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