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  1. 1 point

    What is difference between fouling and scaling?

    In addition to that, most water source used in heat exchanger are not pretreated. Therefore, causing the hard water to deposit calcium carbonate that causes scaling. So a proper water pretreatment could prevent the fouling and scaling altogether. And preventive maintenance should be the best..
  2. 1 point
    Fouling is occure due to the suspended solid like clay in water and scaling is occure due to the dissolved solid like calcium, magnesium in water
  3. 1 point
    In tangential entry dusty gas velocity of dust will drop after colliding with wall of cone and due to higher density of dust they will fall due to centrifugal action as well as gravity force.
  4. 1 point
    Outstanding properties of teflon:- Uses of Teflon and Properties 1. Chemicals includes ozone,chlorine,acetic acid ammonia,sulphuric acid and hydrochloric acid. The coatings are affected by molten alkali metals and highly reactive fluorinating agents. 2. It is weather and UV resistant Teflon 3. It has excellent optical properties 4. It is non stick Very few solid substances can permanently stick to a Teflon coating, where as tacky materials may show some adhesion, almost all substances release easily from the coating. 5. It has outstanding performance at extreme temperatures. Teflon can temporarily withstand temperatures of 260C and cryogenic temperatures of -240C and will then also have the same chemical properties.It has an initial melting point of 342C (+- 10C) temperature. 6. It has low coefficient of friction. Coefficient of friction is the ratio of the force required to make two surfaces slide over each other. A low coefficient of friction equals low resistance and smooth operation. Thus there is no difficulty in sliding one surface against another. The coefficient of friction of Teflon is generally in the range of 0.05 to 0.20, depending on the load, sliding speed, and type of Teflon coating used. 7. Teflon finishes are both hydrophobic and oleophobic, which makes cleanup easier and more thorough. 8. Over many different frequencies, low dissipation factor and high surface resistivity teflon has a high dielectric strength. The high voltage that the insulating material can withstand before it breaks down is its dielectric strength . In addition to it teflon has a low dissipation factor; that is the percentage of electrical energy absorbed and lost when current is applied to an insulating material. A low dissipation factor indicates that the absorbed energy dissipated as heat is low.The high surface resistivity indicates the electrical resistance between opposite edges of an unit square on the surface of an insulating material. Uses of Teflon:- The various market applications of Teflon include : Computer pin belt 1. In electronics industry it is used on account of its insulation property in wires and system components.Also used because of its outstanding electrical performance and durability. Uses for coating 2. Used for metal finishing, paints and coatings,as flour additives can be added to reduce the wear and tear on load-bearing surfaces. For example in inks and lithographic printing, thermoplastics and molded gears, protective industrial surfaces, lubricants to thicken, sterile packaging, etc. Uses as automobile air bags 3. In optical devices, as it can be used as clear coating, requiring a low refractive index and still perform in aggressive chemical environments over a wide range of use temperatures and light waves (UV-IR). For example, it is found in lightweight surgical lamps, photovoltaic cell glazing, etc. 4. In automobiles it finds its uses as airbag systems, fuel hose permeation barrier, fuel system, chassis, brake systems, oil filter, etc. 5. Used as nonstick coating on cooking devices like pans, oven , tawa as it is nonstick and exceptional performance at high temperatures.
  5. 1 point
    If both hx operate in ATM then both vapour pressure is same &upper answer all right...
  6. 1 point
    1.Thermosyphon type HE is vertical HE and Kettle type HE is horizontal HE. 2.in horizontal position, pressure drop is negligible and in vertical position,presuure drop is singnificant and high. 3. If viscosity of bottom product of distillation column is very high then vertical position preferred and if low then horizontal position prefeered. 4 in vetical position high circulation of fluid of posible and low circulation in horizontal positiin.
  7. 1 point
    In HE heat transfer through conductions principle and in cooling tower heat transfer through convention principal.

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