Deposits accumulating in the small channels of a compact heat exchanger affect both heat transfer and fluid flow. Hydrocarbon processing july 2005 heat exchanger fouling is estimated to account for 0. It is not unusual for the u value of a steamtowater shell and tube heat exchanger for hydronic heating to be in the 500 to range before adding fouling. He found out that fouling agents can contain inorganic materials such as airborne dust and grit, waterborne mud and silt, as well as organic materials including biological substances and elemental carbon. Awad 2011 studied the fouling of heat transfer surfaces in general. Counter flow heat exchangers are the most efficient of the three types. Such analysis is prohibitive in terms of computer time.
Pdf method to detect fouling in heat exchangers sylvain. Fouling modeling and prediction approach for heat exchangers. Pdf fouling and fouling mitigation on heat exchanger surfaces. Fouling of a heat exchanger is studied mainly to understand the mechanism of fouling process and to protect the heat exchanging surface so that an uninterrupted operation of the heat exchanger can be achieved without. Fouling is a function of the system and the equipment used.
Fouling is a longstanding problem in refinery due to the detrimental effects that fouling deposits have on thermal and hydraulic performance of the heat exchanger network hen. Assumptions 1 the heat transfer coefficients and the fouling factors are constant and uniform. Fouling of a plate heat exchanger by cheese whey solutions. Maintenance of fouled tubular heat exchangers can be performed by several methods such as acid cleaning, sandblasting, highpressure water jet, bullet cleaning. Pdf fouling of heat transfer surfaces mostafa awad. So, the calculation of the heat transfer that occurs under fouled conditions would require that the basic heat transfer equation be applied at number of points within the. Pdf er fouling of heat exchangers in the dairy industry. Selection of heat exchanger tema layout and number of passes. Fouling results in higher thermal resistance and higher pressure. The fouling factor represents the theoretical resistance to heat flow due to a buildup of a layer of dirt or other fouling substance on the tube surfaces of the heat exchanger, but they are often overstated by the end user in an attempt to minimise the frequency of cleaning. Fouling fouling is the resultant effect of deposition and removal of deposits on a heat exchanger surface. Heat exchanger fouling the problem of fouling is of vital importance to heat exchanger efficiency and should be considered during the design phase of the heat exchanger. Fouling modeling in heat transfer technology, fouling is the. Review of literature on heat transfer enhancement in heat.
The zero fouling heat exchanger explained in this article is derived from the wellknown selfcleaning fluidized bed heat exchange technology where the selfcleaning action is only employed in the tubes. A plate heat exchanger rig was developed at dublin city university to study fouling of plate heat exchangers using cheese whey solutions the rig consisted of an alfalaval plate heat exchanger, 316 stainless steel pipework, pressure and temperature. Detection of fouling in heat exchangers using model. Technologies, design, performance analysis, and building industry trends 1. The net effect of this accumulation on a heat transfer by a fouling factor r f, which is a measure of the thermal resistance introduced by fouling. A fouling a fouling coefficient also is sometimes specif ied, which is the re ciprocal value of th e fouling. U d overall heat transfer coefficient of heat exchanger after fouling wm 2 k u overall heat transfer coefficient of clean heat exchanger wm 2 k 1 can also be expressed as. The foulant layer imposes an additional resistance to heat transfer and the narrowing of the flow area, due to the presence of deposit, results. It causes an increase of capital, operating and maintenance costs. The application of a fouling model in either heat exchanger design or in the simulation of pre heat train performance would appear to require integration over both space and time. Basic heat transfer principles the basic heat transfer relationships that exist for shell and tube exchangers also apply to the design of an aircooled heat exchanger. Fouling is a wellknown problem for forced circulation evaporators for the treatment of waste water. Fundamentally, fouling may be characterized as a combined, unsteady state, momentum, mass and heat transfer. Us2953514a method of reducing heat exchanger fouling.
However, one major phenomenon that limits heat exchanger performance is attributed to fouling. In this paper the authors present a simple approach that. Fouling introduces additional resistance to thermal convection and fluid flow, which leads to higher energy and pump operation cost, especially in crude preheat train. Fundamentally, fouling may be characterized as a combined, unsteady state, momentum, mass and heat transfer problem with chemical, solubility, corrosion and biological processes may also taking place. Its usage in heat exchanger design is based on the insertion of. Gradual deterioration of heat exchanger performance due to the accumulation of fouling film on the heat transfer surface is often accounted for in the form of a fouling resistance, or commonly known as the fouling. The purpose of the present paper is to introduce a novel method to aid in the evaluation of the various parameters that affect the fouling. Often a non fouling heat transfer fluid occurs on the shellside, such as condensing steam. Its usage in heat exchanger design is based on the insertion of additional resistances in the. In a shell and tube heat exchanger, the conventional segment baffle geometry is largely responsible for higher fouling rates. Statistical analysis is used to develop a fouling growth model of a heat exchanger subjected to fouling.
Consider spiral heat exchangers for fouling applications. Specification of tube parameters size, layout, pitch and material. The classical way of solving it is by trial and verification procedures, as in kern 1950, where one first guesses the overall heat transfer coefficient, then chooses the heat exchanger geometry. Fouling on process equipment and heat exchanger surfaces often have a signi. Crystallization fouling often occurs in heat exchangers, especially when using aqueous solutions. Pdf fouling phenomenon and its effect on heat exchanger. Fouling and fouling mitigation on heat exchanger surfaces. Pdf fouling of heat exchangers hamza shafiq academia. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed. The term fouling is usually referred to the accumulation of unwanted deposit on solid surfaces. Little attention was paid to the heat exchanger fouling and the associated inefficiencies of heat exchanger operation till the socalled oil crisis of the 1970s. As fouling develops the overall heat transfer coefficient will vary from point to point within the exchanger. The statistical analysis was considered for four different types of distributions out of which the lognormal distribution was found to be most suitable. In a shell and tube heat exchanger, the conventional segment baffle geometry is largely responsible for higher.
Pdf heat exchangers as a heat transfer device has gained wide applications across different levels of domestic and industrial setups. Experiments were conducted with a single pass shell and tube heat exchanger with water. Kazi published fouling and fouling mitigation on heat exchan ger surfaces find, read and cite all the research you need on researchgate. The clean outlet temperature s are calculated and the u c is reported. The deposition of a thin oil layer on the heat transfer surface and the change of. Lalot heat exchanger fouling and cleaning, 14th to 19th of june, 2009, schladming, austria.
The fouling resistances inside the phe are much lower than that inside the shell and tube heat exchanger. Heat exchanger design is a very important problem in industries. In a fluidized bed heat exchanger the scouring action of a fluidized bed of particles is used to keep the surface clean despite deposition by precipitation and particulate fouling. Incorporating fouling modeling into shellandtube heat. Selection of heat transfer models and fouling coefficients for shell side and tube side. Egr coolers being very prone to fouling during vehicle lifetime. The fouling of heat exchangers may be defined as the accumulation of unwanted deposits on heat transfer surfaces. Fouling of a specific heat exchanger is, besides from the fouling agent. One of the major indeterminates in the design as well as operation of heat exchangers is the rate of fouling a select heat exchanger geometry would exhibit over the operation cycles. The data collected indicate that the primary step in fouling is the adsorption of a monolayer of proteins onto the wall of the heating equipment at room temperature. Detection of fouling in heat exchangers using model comparison. Fouling of heat transfer surfaces is one of the most important problems in heat transfer equipment. What is clearly needed is a much more fundamental approach to the. Introduction hex are designed for thermal processes to work within allowable pressure drop limits and for a specified time period.
Numerical method for heat transfer and fouling analysis of a shell. Figure 2 shows the fouling resistances for cooling water inside a plate heat exchanger in comparison with fouling resistances on the tubeside inside a shell and tube heat exchanger for the same velocity. Us2953514a us688665a us68866557a us2953514a us 2953514 a us2953514 a us 2953514a us 688665 a us688665 a us 688665a us 68866557 a us68866557 a us 68866557a us 2953514 a us2953514 a us 2953514a authority us united states prior art keywords heat exchanger pipe reactor temperature polymer prior art date 19571007 legal status the legal status is an assumption and is. The foulant layer imposes an additional resistance to heat transfer and the narrowing of the flow area, due to the presence of deposit, results in an increased velocity for a given volumetric flow rate. Shell and tube heat exchanger, threshold fouling, fouling. Fouling of heat exchangers in processing industries is a chronic operating problem that compromises energy recovery and maybe environmental welfare. Fouling factors in heat exchangers resources hrs heat. Since the aircooled heat exchanger is exposed to changing climatic conditions, problems. This can only be ascertained and quantified from its effects on various performance parameters of a heat exchanger 8,9. The most common type of a fouling is precipitation of solid deposits in. Bott fouling of heat exchangers chemical engineering. Mitigation of fouling occurrence is frequently hindered by the lack of quantitative knowledge of the dynamic effects of fouling on exchanger heat transfer and pressure drop.
Convective heat transfer coefficient of the hotter side. Jeurnink nizo, 6710 ba ede, netherlands n a general overview is given of the main factors in the fouling of processing equipment used for heating dairy fluids. Pdf fouling pada heat exchanger bayol semprol academia. Fouling and reduced heat transfer in heat exchangers. The thermal resistance and the overall heat transfer coefficients based on the inner and outer areas are to be determined.
Related to heat exchangers, fouling phenomenon occurs specially on heat transfer surfaces and the consequences are not negligible. In fact, fouling has been recognised for a long time, and research on heat exchanger fouling was conducted as early as 1910 and the first practical application of this research was. Numerical method for heat transfer and fouling analysis of a. Based on this, various studies and approaches have focused on reduction, elimination and mitigation. The purpose of our study is to systematically predict the fouling rates of typical residential evaporator coils and to predict the consequent energy and performance impacts. Oily wastewater is also generated during heat exchanger cleaning. The design, installation, commissioning and operation of heat exchangers to minimise fouling. Peningkatan capital costheat exchanger dengan fouling yang tinggi akan menyebabkan pengurangan overall coefficient heat transfer, dengan demikian dibutuhkan luas area perpindahan yang lebih bila dibandingkan dengan fouling yang lebih rendah.
The process of fouling could be represented by the equation 2. The efficiency of the heat exchanger is reduced in respect of heat transfer as a result of the thermal resistance of the deposit. The purpose of the present paper is to introduce a novel method to aid in the evaluation of the various parameters that affect the fouling phenomenon. Luas he yang lebih besar mengakibatkan peningkatan cost. It is equivalent to calculate the individual film heat transfer coefficients for each side of the heat exchanger. Matlab a fundamental tool for scientific computing and engineering applications. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the hottest coldfluid temperature greater than the coldest hotfluid temperatue. As an additional consequence pressure losses are increased abdalla, 2002. Training sensor measurements are obtained of a parameter related to operation of the heat exchanger and a wavelet transform is applied to the training sensor measurements to obtain wavelet data. Some of the authors of this publication are also working on these related projects. The rate of fouling is feed temperature dependent with different rates of fouling between the feed inlet and outlet sides of the heat exchanger. Fouling modeling in heat transfer technology, fouling is the undesired accumulation of deposits over the thermal surface of heat exchanger equipment.
Analysis of heat transfer in heat exchangers by using the ntu method and empirical relations. Fouling in heat exchangers has major cost implications. A method and apparatus for estimating a fouling state of a heat exchanger of an aircraft. Due to various acting deposition mechanisms an insulating layer forms on the gas side of the egr cooler which reduces heat transfer and thus the cooling efficiency of the device. It has been described as the major unresolved problem in heat transfer 1. Kazi published fouling and fouling mitigation on heat exchanger surfaces find, read and cite all the research. Fouling of heat exchangers me485 heat exchanger and steam generator design fouling accumulation of undesirable deposit on a hex surface. The presence of the deposit, in fact, represents another resistance to heat transfer and it is also responsible of the. Parameters which influence the fouling rate in a system include. The fouling factor represents the theoretical resistance to heat flow due to a buildup of a layer of dirt or other fouling substance on the tube surfaces of the heat exchanger, but they are often. Particlesurface interactions in heat exchanger fouling. However, there are more parameters to be considered in the design of an aircooled exchanger. Expired lifetime application number us688665a inventor paul m wilkins.
The u value is the inverse of the resistance in the heat exchanger to heat transfer. This means that the plate heat exchanger can remain in service far longer between cleaning intervals. Heat exchanger fouling and cleaning challenges and. Title of paper heat exchanger fouling and cleaning. Specific heat capacity of air at constant pressure. The fouling factors to be used in the design of heat exchangers are normally specified by the client based on their experience of running the plant or process. Influence of fouling on heat exchanger effectiveness in a.
For typical residential heat pump and air conditioning residential buildings. Pdf use of cfactor for monitoring of fouling in a shell. If uncontrolled, levels of fouling can negate any benefits produced by careful heat exchanger design. Apr 18, 2016 the u value is the inverse of the resistance in the heat exchanger to heat transfer. In fact, fouling has been recognised for a long time, and research on heat exchanger fouling was conducted as early as 1910 and the first practical application of this research was implemented in the 1920s. Fault diagnosis for the heat exchanger of the aircraft environmental control system based on the strong tracking filter article in plos one march 2015 doi. See discussions, stats, and author profiles for this publication at. Setting upper and lower design limits on tube length. The u value is very dependent on the fluid type, the velocity, and the materials of construction. The effect of fouling is considered in heat exchanger design by including the tube side and shell side fouling resistances. Fouling phenomena are common and diverse, ranging from fouling of ship hulls, natural surfaces in the marine environment marine fouling, fouling of heat transfer components through ingredients contained in cooling water or gases, and even the development of plaque or calculus on teeth or deposits on solar panels on mars, among other examples. Fouling detection in a crossflow heat exchanger based on physical modeling o. Investigation into fouling factor in compact heat exchanger.
1400 68 485 1028 817 134 1165 1099 1391 278 1596 277 51 1518 629 9 803 1273 1480 788 497 1665 775 837 612 444 936 244 1298