The Experimental Investigation of Fouling Phenomenon in Heat Exchangers by Heat Transfer Resistance Monitoring (HTRM) Method

2009 ◽  
Author(s):  
M. Izadi ◽  
D. K. Aidun ◽  
P. Marzocca ◽  
H. Lee
Keyword(s):  
Heat Transfer ◽  
Sodium Bicarbonate ◽  
Calcium Chloride ◽  
Heat Exchangers ◽  
Evaluation System ◽  
Quantitative Information ◽  
Fouling Resistance ◽  
Transfer Resistance ◽  
Accelerated Corrosion ◽  
Particulate Fouling

The aim of this paper is to describe a monitoring system for fouling phenomenon in tubular heat exchangers. This system is based on a physical model of the fouling resistance. A mathematical model of the fouling resistance is developed based on the applied thermal heat, the inside heat transfer coefficient, and geometrical characteristics of the heat exchanger under consideration. The resulting model is a function of measured quantities such as water and tube wall temperatures, fluid flow velocities, and some physical properties of the fluid flowing inside the tubes such as viscosity, conductivity, and density. An on-line fouling evaluation system was prepared and the heat transfer resistance for selected solutions was measured in real time by this system. The effect of concentration and chemical reactions on fouling is studied experimentally by using different contaminants such as sodium bicarbonate, calcium chloride, and their mixture. Accelerated corrosion was observed for the calcium chloride-0.4g/l solution due to the presence of chlorine ions. This corrosion-fouling can be mitigated by adding sodium bicarbonate. However, calcium carbonate is formed as the result of the chemical reaction between calcium chloride and sodium bicarbonate which activates two other fouling categories, particulate fouling and crystallization. The inside surface of the tube is analyzed by analytical microscopy after the experiment to investigate different fouling categories. Experimental results provide quantitative information of liquid-side fouling on heat transfer surfaces, and its effects on the thermal efficiency. Experimental data is significantly important for the design, and for formulating operating, and cleaning schedules of the equipment.

The Experimental Investigation of Fouling Phenomenon in Tubular Heat Exchangers by Heat Transfer Resistance Monitoring (HTRM) Method

2008 ◽  
Author(s):  
M. Izadi ◽  
D. K. Aidun ◽  
P. Marzocca ◽  
H. Lee
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Evaluation System ◽  
Tube Wall ◽  
Quantitative Information ◽  
Fouling Resistance ◽  
Output Data ◽  
Transfer Resistance ◽  
Geometrical Characteristics ◽  
On Line

The aim of this paper is to describe a monitoring system for fouling phenomenon in tubular heat exchangers. This system is based on a physical model of the fouling resistance. A mathematical model of the fouling resistance is also developed based on applied thermal heat, the inside heat transfer coefficient and geometrical characteristics of the heat exchanger. The resulting model is a function of measured quantities such as water and tube wall temperatures, fluid flow velocities, and some physical properties of the fluid flowing inside the tubes such as viscosity, conductivity, and density. An on-line fouling evaluation system has been prepared and heat transfer resistance for selected solutions has been measured in real time by this system. Experimental results provide quantitative information of liquid-side fouling on heat transfer surfaces, and its effects on the thermal efficiency. Output data is significantly important for the design, and for formulating operating and cleaning schedules of the equipment.

Experimental Investigation of Fouling Behavior of 90/10 Cu/Ni Tube by Heat Transfer Resistance Monitoring Method

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
M. Izadi ◽  
D. K. Aidun ◽  
P. Marzocca ◽  
H. Lee
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Sodium Bicarbonate ◽  
Calcium Chloride ◽  
Monitoring System ◽  
Heat Exchangers ◽  
Experimental Results ◽  
Fouling Resistance ◽  
Transfer Resistance ◽  
Wide Range

Abstract This paper describes an advanced monitoring system for fouling phenomenon in a wide range of tubular heat exchangers such as condensers and intercoolers. First, a mathematical model of fouling resistance in tubular heat exchangers is adapted. The model is based on the applied thermal power, the inside heat transfer coefficient, and geometrical characteristics of the heat exchanger under consideration. The resulting model is a function of measured quantities such as water and tube wall temperatures, fluid flow velocity, and some physical properties of the fluid flowing inside the tubes, such as viscosity, conductivity, and density. Second, an on-line fouling monitoring system was prepared, and the heat transfer resistance for selected solutions was measured in real time by this system. The effect of concentration and chemical reactions on fouling was studied experimentally using contaminants such as sodium bicarbonate, sodium chloride, calcium chloride, and a mixture of sodium bicarbonate and calcium chloride. Experimental results provide quantitative information of liquid-side fouling on heat transfer surfaces, and its effects on the thermal efficiency. Experimental data are critical for heat exchanger design and for planning operating and cleaning schedules of the heat exchanger. Uncertainty analysis shows that the experimental results are acceptable and the experimental setup is appropriate for measuring fouling resistance in industrial applications.

Enhanced Gas-Side Heat Transfer in Rectangular Micro-Honeycombs

2012 ◽  
Author(s):  
Shankar Krishnan ◽  
Steve Leith ◽  
Terry Hendricks
Keyword(s):  
Heat Transfer ◽  
Power Systems ◽  
Heat Exchangers ◽  
High Performance ◽  
Heat Transfer Performance ◽  
Low Cost ◽  
Transfer Performance ◽  
Thermo Electric ◽  
Transfer Resistance ◽  
Heat Transfer Augmentation

Gas and air-side heat transfer is ubiquitous throughout many technological sectors, including HVAC (heating, ventilating, and air conditioning) systems, thermo-electric power generators and coolers, renewable energy, electronics and vehicle cooling, and forced-draft cooling in the petrochemical and power industries. The poor thermal conductivity and low heat capacity of air causes air-side heat transfer to typically dominate heat transfer resistance even with the use of extended area structures. In this paper, we report design, analysis, cost modeling, fabrication, and performance characterization of micro-honeycombs for gas-side heat transfer augmentation in thermoelectric (TE) cooling and power systems. Semi-empirical model aided by experimental validation was undertaken to characterize fluid flow and heat transfer parameters. We explored a variety of polygonal shapes to optimize the duct shape for air-side heat transfer enhancement. Predictions using rectangular micro-honeycomb heat exchangers, among other polygonal shapes, suggest that these classes of geometries are able to provide augmented heat transfer performance in high-temperature energy recovery streams and low-temperature cooling streams. Based on insight gained from theoretical models, rectangular micro-honeycomb heat exchangers that can deliver high performance were fabricated and tested. High- and low-cost manufacturing prototype designs with different thermal performance expectations were fabricated to explore the cost-performance design domain. Simple metrics were developed to correlate heat transfer performance with heat exchanger cost and weight and define optimum design points. The merits of the proposed air-side heat transfer augmentation approach are also discussed within the context of relevant thermoelectric power and cooling systems.

Second-Law-Based Thermoeconomic Optimization of Two-Phase Heat Exchangers

1987 ◽  
Vol 109 (2) ◽  
pp. 287-294 ◽  
Author(s):  
S. M. Zubair ◽  
P. V. Kadaba ◽  
R. B. Evans
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Unit Cost ◽  
Second Law ◽  
Inlet Temperature ◽  
Two Phase ◽  
Transfer Resistance

This paper presents a closed-form analytical method for the second-law-based thermoeconomic optimization of two-phase heat exchangers used as condensers or evaporators. The concept of “internal economy” as a means of estimating the economic value of entropy generated (due to finite temperature difference heat transfer and pressure drops) has been proposed, thus permitting the engineer to trade the cost of entropy generation in the heat exchanger against its capital expenditure. Results are presented in terms of the optimum heat exchanger area as a function of the exit/inlet temperature ratio of the coolant, unit cost of energy dissipated, and the optimum overall heat transfer coefficient. The total heat transfer resistance represented by (1/U = C1 + C2 Re−n) in the present analysis is patterned after Wilson (1915) which accommodates the complexities associated with the determination of the two-phase heat transfer coefficient and the buildup of surface scaling resistances. The analysis of a water-cooled condenser and an air-cooled evaporator is presented with supporting numerical examples which are based on the thermoeconomic optimization procedure of this paper.

Mitigation of Particulate Fouling by Ozonation

2003 ◽  
Vol 125 (1) ◽  
pp. 147-150 ◽  
Author(s):  
Bang-Yenn Wu ◽  
S. H. Chan
Keyword(s):  
Heat Transfer ◽  
Calcium Carbonate ◽  
Cooling Tower ◽  
Cooling Water ◽  
Reynolds Numbers ◽  
Fouling Resistance ◽  
Low Reynolds Numbers ◽  
Particulate Fouling ◽  
High Reynolds ◽  
Deposit Layer

Heat transfer surface fouling introduces a major uncertainty into the design and operation of cooling water systems. Fouling caused by calcium carbonate CaCO3 typically occurs on heat transfer surfaces. Ozone has been successfully used for more than 90 years as a disinfectant in drinking water. Recently, it has been proposed to use ozone for cooling tower water treatment. In this research, the effectiveness of mitigation of calcium carbonate particulate fouling by ozone was studied systematically. The experimental results show that, at low Reynolds numbers, though the ozonation retards the initial calcium carbonate particulate fouling rate, the retardation led to a non-porous deposit layer and a higher asymptotic fouling resistance. However, at high Reynolds numbers, ozonation was found to reduce the asymptotic fouling resistance.

scholarly journals Introducing a holistic approach to model and link fouling resistances

2020 ◽  
Author(s):  
Florian Schlüter ◽  
Wolfgang Augustin ◽  
Stephan Scholl
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Holistic Approach ◽  
Detailed Knowledge ◽  
Fouling Resistance ◽  
Scientific Investigations ◽  
Double Pipe ◽  
Analytical Approaches ◽  
To Receive ◽  
Pipe Heat

AbstractFouling is the unwanted deposition of soils on heat transfer surfaces and is a major challenge for industry and has been s subject to scientific investigations for decades, still being an unsolved problem for many applications. A fouling situation is commonly quantified with the thermal fouling resistance describing the integral fouling behavior of an apparatus. Modeling of this quantity is a permanent subject to research. This contribution presents the basics of an expanded consideration by introducing a holistic approach to model and link fouling resistances based on the extension of previous work in this field. A thermal and a mass based approach to calculate fouling resistances are considered integrally and locally. This will provide a detailed knowledge of the fouling behavior. Various variables are needed for modeling the different fouling resistances. Therefore, both experimental and analytical methods have to be applied to obtain the required data regarding local differences of crystallization deposits within double-pipe heat exchangers. Here the planned experimental and analytical approaches to receive all the required input data are described, also presenting the required test equipment briefly. Core equipment is a test rig equipped with double pipe heat exchangers, which allows the measurement of thermal and fluid flow related values and provides samples for the analysis of the fouling deposits. Furthermore, the aim of the new modeling concept is to link integral and local fouling resistances by taking into account locally varying parameters regarding the fouling layer. In order to allow for that, a recalculation of the thermal fouling resistance into a corrected version by considering heat transfer enhancing effects attempts to correlate with the mass based approach in a first step. In the end, the holistic modelling approach is presented.

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