Scaling of Heat Exchanger Tubes by Calcium Carbonate

1975 ◽  
Vol 97 (4) ◽  
pp. 504-508 ◽  
Author(s):  
A. P. Watkinson ◽  
O. Martinez
Keyword(s):  
Heat Exchanger ◽  
Calcium Carbonate ◽  
Mathematical Models ◽  
Flow Velocity ◽  
Test Section ◽  
Suspended Solids ◽  
Bulk Temperature ◽  
Fouling Resistance ◽  
Steam Temperature ◽  
Scaling Process

Scaling of copper heat exchanger tubes has been studied under conditions that promote rapid and severe scaling. Artificially hardened water of high dissolved and suspended solids is recirculated through a heated test section operated at constant steam temperature. The effects of flow velocity, tube diameter, and bulk temperature on the asymptotic fouling resistance have been determined. Results are interpreted in terms of mathematical models of the scaling process.

Scaling of Plain and Externally Finned Heat Exchanger Tubes

1986 ◽  
Vol 108 (1) ◽  
pp. 147-152 ◽  
Author(s):  
R. Sheikholeslami ◽  
A. P. Watkinson
Keyword(s):  
Heat Flux ◽  
Heat Exchanger ◽  
Calcium Carbonate ◽  
Mild Steel ◽  
Constant Heat Flux ◽  
Steel Tube ◽  
Scale Formation ◽  
Fouling Resistance ◽  
Constant Heat

The performance of copper and mild steel plain heat exchanger tubes and an externally finned mild steel tube was studied under calcium carbonate scaling conditions. Under a constant heat flux for 70-h periods the fouling resistance generally increased linearly with time. The effect of velocity on the rate of scale formation is presented for the three tubes and results compared with the model of Hasson.

Numerical Study of Fluid Flow and Heat Transfer Enhancement of Nanofluids over Tube Bank

2013 ◽  
Vol 388 ◽  
pp. 149-155 ◽  
Author(s):  
Mazlan Abdul Wahid ◽  
Ahmad Ali Gholami ◽  
H.A. Mohammed
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cross Flow ◽  
Bulk Temperature ◽  
Compact Heat Exchanger ◽  
Pure Fluid ◽  
Tube Banks

In the present work, laminar cross flow forced convective heat transfer of nanofluid over tube banks with various geometry under constant wall temperature condition is investigated numerically. We used nanofluid instead of pure fluid ,as external cross flow, because of its potential to increase heat transfer of system. The effect of the nanofluid on the compact heat exchanger performance was studied and compared to that of a conventional fluid.The two-dimensional steady state Navier-Stokes equations and the energy equation governing laminar incompressible flow are solved using a Finite volume method for the case of flow across an in-line bundle of tube banks as commercial compact heat exchanger. The nanofluid used was alumina-water 4% and the performance was compared with water. In this paper, the effect of parameters such as various tube shapes ( flat, circle, elliptic), and heat transfer comparison between nanofluid and pure fluid is studied. Temperature profile, heat transfer coefficient and pressure profile were obtained from the simulations and the performance was discussed in terms of heat transfer rate and performance index. Results indicated enhanced performance in the use of a nanofluid, and slight penalty in pressure drop. The increase in Reynolds number caused an increase in the heat transfer rate and a decrease in the overall bulk temperature of the cold fluid. The results show that, for a given heat duty, a mas flow rate required of the nanofluid is lower than that of water causing lower pressure drop. Consequently, smaller equipment and less pumping power are required.

Design of a Heat Exchanger and Temperature Homogenization Device for Airflow in Chamber

2012 ◽  
Vol 271-272 ◽  
pp. 1281-1285
Author(s):  
Wei Guan ◽  
Xiao Feng Meng ◽  
Deng Feng Dong
Keyword(s):  
Heat Exchanger ◽  
Field Analysis ◽  
Bulk Temperature ◽  
Temperature Uniformity ◽  
Practical Applications ◽  
Evaluation Indexes ◽  
Transfer Capability ◽  
Airflow Field ◽  
Temperature Homogenization ◽  
Independent Heat

Traditional heat-exchanger can ensure the air in chamber a specific bulk temperature, but cannot guarantee the temperature distribution is even. A heat exchanger and temperature homogenization device was designed to precisely adjust the temperature and temperature uniformity of airflow. The device was made up of several parallel processing units. Each unit was an independent heat exchanger with temperature homogenization function. To improve the design of the device, evaluation indexes were proposed for both heat transfer capability and temperature uniformity of the airflow field. Analysis and comparison of 3D numerical simulations using FLUENT were made to figure out the optimal way. The model proposed can provide guidance for practical applications. The final results indicate field synergy principle can be used to analyze the temperature homogenization of airflow.

Analysis and Verifications for Meso-Scale Heat Exchanger With Magneto-Hydrodynamic (MHD) Pumps

2003 ◽  
Author(s):  
Pei-Jen Wang ◽  
Chia-Yuan Chang
Keyword(s):  
Heat Exchanger ◽  
Flow Velocity ◽  
Heat Exchangers ◽  
Cooling System ◽  
Cooling Capacity ◽  
Magnetic Flux Density ◽  
Electrically Conducting ◽  
Experimental Apparatus ◽  
Explicit Finite Difference ◽  
Flow Velocity Of Coolant

Electronic devices have been mainly relying on passive heat exchangers to transfer heat away for preventing catastrophic thermal runaway. However, the passive heat exchangers usually provide limited cooling capacity due to spatial limitations of the target systems. In this paper, an active heat exchanging system, based upon MHD pumping principle for driving electrically conducting coolant without utilizing mechanical moving-parts, was studied and experimentally verified. Governing equations of electrically conducting liquids driven by the Lorentz forces were derived by assuming steady state, incompressible and fully developed laminar flow conditions. Furthermore, numerical simulations were conducted with the explicit Finite-Difference Method to evaluate the performance of the heat exchanger. Finally, an experimental apparatus was built for measuring the flow velocity of coolant and the associated total cooling capacity. A significant flow velocity of 1.09 × 102 mm/s at 3 Ampere applied current was observed when the magnetic flux density was kept at 0.4 Tesla. The experimental results concluded that the heat exchanger consumed very low electric power; hence, the cooling system is very promising for applications in micro-fluidic systems.

The Effect of Flat Bar Supports on the Crossflow Induced Response of Heat Exchanger U-Tubes

1983 ◽  
Vol 105 (4) ◽  
pp. 775-781 ◽  
Author(s):  
D. S. Weaver ◽  
W. Schneider
Keyword(s):  
Heat Exchanger ◽  
Wind Tunnel ◽  
Flow Velocity ◽  
Triangular Array ◽  
Induced Response ◽  
Elastic Instability ◽  
Pitch Ratio ◽  
Wind Tunnel Study

A wind tunnel study was conducted to determine the effect of flat bar supports on the crossflow induced response of heat exchanger U-tubes. The 13-mm-dia tubes formed a triangular array with a pitch ratio of 1.57 and a mean U-bend diameter of about 1.5 m. A 0.3-m-long section of the array was exposed to a flow parallel to the plane of the U-bends. Experiments were conducted with no supports, with one set of flat bars at the apex, and with two sets of flat bar supports at the apex and 45 deg points. In each case, the tube response was monitored to a flow velocity beyond that required for fluid elastic instability. Limited experiments were also conducted to examine the effect of tube support clearance on tube response. Conclusions are drawn regarding the effectiveness of flat bars as U-bend antivibration supports.

Study on the Methods of Predicting the Fouling Characteristics of Plate Heat Exchanger Based on Water Quality Parameters

2013 ◽  
Vol 459 ◽  
pp. 153-158
Author(s):  
Xiao Qiang Wen
Keyword(s):  
Water Quality ◽  
Heat Exchanger ◽  
Experimental System ◽  
Quality Parameters ◽  
Plate Heat Exchanger ◽  
Water Quality Parameters ◽  
Fouling Resistance ◽  
Plate Heat ◽  
The Impact ◽  
Fouling Characteristics

Fouling characteristic of plate heat exchanger was studied through the experimental system, with the Songhua River water as working fluid. Several water quality parameters: pH value, conductivity, dissolved oxygen, turbidity, hardness, alkalinity, chloride ion, iron ion, chemical oxygen demand, total bacterial count, which had great influence on the formation of fouling, as well as running condition, fouling resistance and other parameters were measured through the experimental system built. A group of fouling data of the typical water quality was obtained. Two prediction models of fouling characteristics of the plate heat exchanger were built based on partial least squares algorithm (PLS) and support vector regression machine (SVR) with water quality parameters as independent variables and fouling resistance as dependent variable, and the impact of water quality parameter on predicting accuracy was analyzed. Research results showed that: the prediction accuracy of two methods could be controlled within 12.5% and meet the requirements of the project. Through the comparison of the prediction results, it was proved that the SVR method was better than the method of PLS. The impact of the water quality parameters on prediction model was discussed by the means of deleting the water quality parameters one by one.

Statistical Aspects of CaCO3 Fouling in AISI 316 Stainless-Steel Tubes

1997 ◽  
Vol 119 (3) ◽  
pp. 581-588 ◽  
Author(s):  
S. M. Zubair ◽  
A. K. Sheikh ◽  
M. O. Budair ◽  
M. U. Haq ◽  
A. Quddus ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Cooling Water ◽  
Basic Mechanism ◽  
Experimental Program ◽  
Fouling Resistance ◽  
Steel Tubes ◽  
Experimental Apparatus ◽  
Hydraulic Conditions ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

Calcium carbonate fouling is typically encountered in a cooling-water circulating system. An experimental program is initiated to study fouling growth law (s) as well as the basic mechanism of calcium carbonate (CaCO3) scaling. After a brief description of the experimental apparatus and procedure for calculating fouling resistance, we present the deposition data in terms of fouling resistance as a function of time taken at different sections of the tube. In addition, the randomness of fouling growth is illustrated by repeating the experiments several times under the same thermal-hydraulic conditions. The results are presented in terms of a set of sample functions and their associated probability density functions at various levels of fouling. In addition, basic mechanism of CaCO3 scale formation is also explained through Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX).

Crystallization Fouling in Plate Heat Exchangers

1993 ◽  
Vol 115 (3) ◽  
pp. 584-591 ◽  
Author(s):  
B. Bansal ◽  
H. Mu¨ller-Steinhagen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Velocity ◽  
Wall Temperature ◽  
Heat Exchangers ◽  
Calcium Sulfate ◽  
Surface Reaction ◽  
Heat Transfer Surface ◽  
Plate Heat

Crystallization fouling of calcium sulfate was investigated in a plate and frame heat exchanger. The effects of flow velocity, wall temperature, and CaSO4, concentration on the fouling rates have been investigated and the distribution of scale along the heat transfer surface has been observed. The measured fouling curves are compared with predictions from a surface reaction controlled model.

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