1. F

    heat exchange between a tube and a box

    The problem is very easy but i cannot figure it out. I have a tube of L length, Dext and Dint. The tube is in a box of x,y,z dimensions. The box has a constant temperature of 37°C and it is full of water. The tube is inside the box and in the tube there is a flow of water. The Tin of the tube...
  2. F

    Discretization of heat exchanger

    Hi. I hope my description of the problem will be sufficient. I'm trying to make an analytical model of a heat exchanger. The hex is a coil wound type, (helical coil) with several pipes in parallel to reduce the pressure loss, it is double. Meaning it takes it's turns (windings)...
  3. Y

    Specific heat

    A 100gm copper block is heated is boiling water for ten minutes and then it is dropped into 150gm of water at 30Cels. In a 200gm of Calorimeter. If the temperature of water is raised to 33.6 Cels. Determine the specific heat of material of the calirometer. Copper specfic heat 386 and water...
  4. J

    Heat exchanger

    At work, we have a tube and shell heat exchanger. The fluid to be heated is water and the other fluid is steam. -------------------------------------- Theoretical ... Btu / h: 136.1 x10 ^ 6 Flow Steam: 136,000 pph (I think it's pound per hour) Ti of the steam: 312 F To the steam: 212 F Psi...
  5. N

    Heat Insulation Experiment

    I'm doing some experiments on heat insulation with a model house (made of styrofoam, 3cm), heated with a 25W light bulb. In some papers I have read that it's important for the box to be two-layered, with only the outer layer being styrofoam and the thin inner layer consisting of material with a...
  6. B

    Color fringes on heated plate

    I've recently noticed that the ceramic plates I have home show an interesting light pattern whenever light is reflected on a slightly heated area of them. The setup is the following: a ceramic plate, a lightbulb a meter above it, and any means of heating such as blowing hot air or putting hot...
  7. A

    How much heat is required to turn ice into water vapour?

    This is the question: "How much heat is required to turn 1.5 kg of water ice at a temperature of −25°C into 1.5 kg of water vapour at 150°C? (to 2 s.f and in MJ) [cice = 2090 J kg−1 K−1, cwater = 4190 J kg−1 K−1, cwater-vapour = 2010 J kg−1 K−1, Lvap-water = 2256×103 J kg−1, Lfus-water =...
  8. E

    Water-air heat transfer

    Experiment: The air currents of two large domestic fans were directed toward the water surface of a 50-gallon tank while the ambient temperature was 88°F. If at the beginning of the experiment the water was at 77°F, why did this temperature drop? Shouldn't it have been the other way around...
  9. J

    Accelerated heat transfer test

    Hi everyone! I want to keep a pharma product between 2-8°C for 48 hrs in a 30°C ambient using an insulated box with ice packs in it. If I want to reduce my test time to 8 hrs, by how much should I raise the testing ambient temperature to get valid results as if it was a 48 hr 30°C test? As...
  10. R

    Heat transfer between flue gas and feed water?

    I need to determine the temperature of flue gas in a fire tube boiler. Tube inlet gas temperature, T1 = 1045 deg.C Saturation water temperature, tsat = 186 deg.C Flue gas temperature, t2 = ? 2 equations to be used here: Q = U.A.LMTD -------------(1) Qg = Mg.Cg.(T1 - T2) ------(2)...
  11. E

    Heat transfer between 3 bodies

    Hi i have problem i want to solve that is related to an industry. The problem is that i have 3 rectangular wood plates. The middle plate starts with 120c degrees. The upper and lower plate are being constantly cooled so they keep a temperature of 20 degrees celsius all the time. The question i...
  12. B

    Heat loss within a control volume

    Hello, I have the following problem: I got an electrical component within a chamber and the chamber has an opening, where air can be supplied from and an outlet. Attached you can see an illustration of the problem. The electrical component has a heat loss of 150 W The temperature at...
  13. mscfd

    Heat conduction problem

    Here is the question: Consider a pool reactor (Fig. 2-33) whose core is constructed from a number of vertical fuel plates of thickness 2L. Initially the system has the uniform temperature T; then assume that the constant nuclear internal energy u"' is uniformly generated in these plates. The...
  14. F

    Heat Transfer

    Please help clarify which is the correct answer and or method to the following problem: Ideally, when a thermometer is used to measure the temperature of an object, the temperature of the object itself should not change. However, if a significant amount of heat flows from the object to the...
  15. T

    Heat of Reaction (Enthalpy)

    Well, suppose we have a reaction: |\nu _1| A_1 +|\nu _2| A_2+\cdots \rightleftharpoons |\nu _3| A_3 +|\nu _4| A_4 +\cdots At standard conditions (P_0,T_0)=(1 bar , 298.15 K ) we calculate the enthalpy of reaction via tabulated values of enthalpy of formation: \Delta...
  16. D

    Adiabatic intersection with graph

    I found the graph above of an ideal gas's transformation in a book, and it says that between 1-2 the heat (Q) is positive and at point 2 it is 0, which I understand because it's an adiabatic intersecting that and after that it becomes negative. Why is it first bigger than 0 and then smaller?
  17. K


    In a thermally insulated environment, there is water with a mass of 200 gr at 20 degrees Centigrate.We drop 60 grams of ice into the water with a temperature of -40 degrees. If thermal equilibrium is maintained find the mass of ice and water in the environment? I found the answer as...
  18. R

    Heat Transfer

    Hello, all. I'm a newbie in physics and am looking to pursue mechanical engineering as a degree. Thermodynamics is very interesting, but I'm stumped on a question without any way to test it out. This isn't for school, but rather for my own studies. Does the presence of heat in a conductor...
  19. K

    heat engines

    A heat engine has a thermal efficiency of 40% at a steady power output of 30 kW. Calculate the required volumetric fuel flow in l/hr (litres/hour) if the fuel has a density of 850 kg/m3 and an energy content of 45MJ/kg
  20. C

    Finding volumetric flow rate of heat engine

    A Heat Engine has a thermal efficiency of 40% at a steady power output of 30kW. Calculate the required volumetric fuel flow in L/Hr ( litres/hour) if the fuel has a density of 850 kg/m^3 and an energy content of 45 MJ/kg.