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Chew, S. A major problem in industries that use heat exchanger equipment cooled with water in their industrial processes is biofouling. In the design and operation of heat exchangers cooled with water, a … Expand. On-line cleaning technique for mitigation of biofouling in heat exchangers: A case study of a hydroelectric power plant in Brazil.
Abstract An experimental methodology was developed to assess an on-line cleaning technique to mitigate biofouling in plate heat exchangers. The exchangers are used in the cooling system of the … Expand. View 1 excerpt, cites background. Fouling mitigation in food processes by modification of heat transfer surfaces: A review. Abstract In most industrial processes, heat exchangers are used for preheating, condensation and evaporation. Within these apparatuses, undesirable deposits often form.
These deposits are known as … Expand. Heat Exchangers HEs are used widely in industries where transfer of heat between two or more mediums is a necessity. The fouling of a heat exchanger is a natural phenomenon and depends upon various … Expand. Applied Thermal Engineering. Abstract Biofouling is an undesirable phenomenon in heat exchangers, which adheres slowly and progressively to the inner surface of the tubes, results in a reduction of the heat transfer, and … Expand.
Fouling is generally defined as the accumulation and formation of unwanted materials on the surfaces of processing equipment, which can seriously deteriorate the capacity of the surface to transfer … Expand. Heat exchangers are widely used in heating, air conditioning, refrigeration, industrial plants and refineries, gas processing and water treatment. Fouling is a chronic operating and design problem … Expand. Due to hardness of cold water supply in many countries, there is a risk of fouling in domestic hot water DHW counterflow plate heat exchangers.
The scaling will result in increased resistance to … Expand. Received: 2 October Accepted: 5 November This paper aims to give a new analysis approach of the crude oil fouling phenomenon through CFD. Heat exchangers are analyzed in order to evaluate … Expand.
View 3 excerpts, cites background. Heating or cooling of one medium by another medium is performed in a heat exchanger along with heat dissipation from surfaces of the equipment. Mass flow, heat in a controlled environment. In the following sections an transfer coefficient as well as the inflow temperatures introduction will be given to the model used for simula- can be time dependent.
Dynamic simulation model The mathematical model of a general heat exchanger specifies the fluid temperature as position dependent Simulation of fouling fields inside the heat exchanger, where energy travel in two ways: Resistance to heat transfer is the inverse of U. It is as- sumed that the conduction within each fluid is neg- ligible. To compare the effect of the metal what U would be for a clean heat exchanger. In Figure the output temperatures where calculated for with and U ouled 2 the ratio Ufclean is shown.
In 7 it is shown that foul- without the metal sheet with the same input tempera- ing increases with time, to simulate this effect the foul- ture and mass flow. In Figure 2 it can clearly be seen that the x and y direction respectively.
The width of the ex- accumulation of fouling starts slowly but increases with changer is W , the height is H and the thickness of the time. The The effect of fouling on U is calculated in the simulation energy balance for this system is described by two cou- with Eq.
The constant cf 2 indicates when Sample no. The values of cf 1 and cf 2 can be between [0, 1]. According to 1 a fouling factor for water is The slope method, described above, is derived to de- typically in the range [0.
Typical values tect fouling in heat exchangers which usually have small for the fouling factor can be found at For the variation in their inlets, as is the case for district heat- data used in this study the fouling factor on the pre- ing heat exchangers. In district heating systems all the viously mentioned interval corresponds to the interval inlets have small variations except the cold mass flow.
In Figure 3 the The cold mass flow varies with water demand. To simu- corresponding fouling factor is shown. Simulation data The effect of fouling was allowed to decrease the overall The simulated heat exchanger was 0. The reason for these dimensions As has been mentioned previously, the method monitors was to insure turbulent flow in the simulated heat ex- changes in the slope AU F by comparing it to a reference changer.
In Figure 5 typical estimation of the reference by randomly choosing base points over certain interval. The temperatures and the mass flows where then al- In Figure 6 the changes in the slope, AU F , is moni- lowed to vary between the base points by interpolating tored. The straight black line is the reference slope and randomly between the base points.
In all the data simulations the same fouling effect was The above figure shows all the data points from all the used, in order to be able to compare the results for the windows the slope AU F is estimated from, in the lower methods and to do sensitivity analysis on their results.
To represent a to show how the slope is changing in time. If the slope heat exchanger in a district heating system only small is decreasing it may mean that the heat exchanger is variations in the inlets were allowed. Figure 4 shows accumulating fouling or that the inputs have changed.
Figure 7 shows Fig. The CuSum charts detects shifts in the slope at 0. Sensitivity analysis on detection It can be shown that the mass flow has considerable ef- fect on the heat transfer. This effect can influence the detection of fouling. This interval corresponds to a fouling factor on the interval [0. In the case where the 2. These two cases explain the wide range 0. Solution to this problem might be to have a longer reference interval. As mentioned above heat ex- changers are designed to account for the effects of foul- ing by incorporating a fouling factor.
The fouling factor indicates the maximum fouling the heat exchanger can sustain and still fulfill it operational requirements. The fouling factor is usually on the interval [0. Proceedings of the 6th International Conference on Heat The detection analysis was only used on the fouled part Exchanger Fouling and Cleaning.
Wiehe, M. Hyland, X. The main results were the following: Chen and B. Bansal Proceedings of the 6th Interna- changer with a small variation of the inlet variables.
Jeynes, Q. Zhao and H. Muller- is [0. Ion Implantation of Stainless Steel responds to the fouling factor interval [0. In: Ion Im- 0. The slope method can be used to detect fouling in [12] Heronimo, M.
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