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Hi all! Digging on the subject i found in several situations with real manufacturers data, that the mechanical (shaft) power output is much more higher than the the one that we calculate using the isentropic efficiency. For instance, i can get the following values, as an example: - Isentropic...

Hi everyone, I'm ending some calculations of a helical coil immersed in a liquid solution. Inside the tube runs superheated steam that condensates along it. Here i don't have problems, even though we're talking about condensation. My problem is to calculate the heat transfer coef. outside the...

Hi, I'm making some heat transfer calculations, to determine a steam coil to heat a phosphoric acid tank. For this i need the coefficient of expansion of this acid. I've searched a lot but i didn't find anything. Does anyone have a value?? Thanks

Hi, i have de following situation: vertical diesel tank with aprox. 7m height above the outlet. next i have a coalescent filter that has a pressure drop of 0,4 bar (clean) to 1,0 bar (change-out). next i have a pump for 50 l/min and 0,6 bar head. it pumps to a consumer at 50m distance and with...

Hi, I have a specific situation to study but i would like to receive some opinions and i will put the question in a very basic way so that i can start from scratch. I've attached a pdf file with a simple drawing. Assumptions: - Both pair of pumps are working at 50Hz - Each pair of pumps has...

Hi, I can't find anything to calculate the thermodynamic propertis of gas mixtures, like: Butane, propane, pentane, ethylene, methane, hydrogen, etc. Is there any website where i can do this? Can anyone help me?

Hi, In attach i put an image with my heat transfer problem. Please take a look... Until now, i made 2 simulations: 1- assuming heat transfer problem for parallel flows A and B, assuming B2 as 40ºC and B2 as 9ºC i've obtained a water flow of 6kg/h 2 - assuming radial conduction from surface of...

Hi, I'm doing some precise calculations for a heat transfer problem with a propane gas stream. I need the specific heat of propane gas for different temperatures, say for example form 10ºC to 50ºc. I found a great website, but the values of enthalpy for example are quite different from what i...

Some time ago, here in this forum i posted a thread asking about how to calulate heat loss from valves. At that time my problem was solved through a document that i attach (see page 6-8, Table 4). I've used this values, but recently i used them once more and see some strange results and i...

Hi, I would like to know if there is any effective improve (or not) in a boiler efficiency after a conversion from fueloil to natural gas. Thanks

Hi, I want to use an automatic blowdown system and use it's waste energy, in a boiler that produces 6.400 kg/h at 10 barg. A typical use for this kind of situations as it is showed in the image that i've attached. My question is if the boiler feed water tank is atmospheric what is the pressure...

Hi, I usually make some combustion calculations for boilers using different fuels: natural gas, fuel oil, biomass, etc. In every chamical analysis that i make, anf from what i have learned, combustion products are allways the same: CO2, H20, N2 and O2. But, i have a question: what about other...

Hi, I want to know how much can a boiler efficiency be improved by using a modulating burner vs a min/max. I know that they are more suitable depending in the rate of the boiler, but for example, if we have a boiler with a burner capable of working in modulating mode, but it works now in a...

Hi, I have a simple question: i have an exhaust gas of a combustion chamber that uses natural gas and i want to use it to heat the combustion air. What are your opinions regarding this 2 options: 1) Install an gas-air heat exchanger 2) Install an gas-water heat exchanger and a water-air heat...

Hi, I would like to hear some opinions about this situation. Gived data I have a pump with max head of 50mH2O (S.I.units) and in it's working point in this specific circuit is of aprox. 35mH2O. Question What happens to the pump outlet pressure when the system is turned ON, if i have a 2bar...

Hi, I have a Excel sheet wich calculates the insulation thickness, so that the surface temperature reaches, a user defined temperature, for example 40ºC, for safety reasons. It happens 2 things that i consider quite strange: 1) What some people say is that as lower is the pipe diameter the...

Hi, I would like to perform some detailed calculations to determine the energy saving in the appliance of a VSD (variable speed drive) in electric motors mainly for pumps. I searched in many references and there are some explanations, but i didn't find yet one that suits for my intentios...

Hi, I'm trying to calculate the possible heat recovery from a room where are installed air compressors. All the books and references that i found approaches this problem the same way: considers 80% of the air compressor power recoverable. Althoug this approach may be correct, i would like to...

Hi, I'm fighting here with steam leak calculations. I found 3 or 4 different methods and the results are far from consistent. Is there any standard that guides to the correct formula, or does anyone know the correct formula to calculate it? Thanks!

Hi, I'm calculating some valves heat loss. Until now, i have been using a calculation method that uses a conversion from the valve diameter to equivalent pipe length, and then calculate normally as if it is a pipe. Now i'm trying to validate this conversion factors, or to make some more...