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@Snickster, Ok thanks for the information, that was my thought on the ph chart which matches with the compressor data i have. I still don't understand why in the superheated tables at the same pressure and temperature the enthalpy is more like...

Here is the condition on the pH chart.https://files.engineering.com/getfile.aspx?folder=77ecdcf1-5a4a-457a-a71e-ff1ee2feb3cc&file=r134a_point.png

Hi all, I'm sure there is a really easy answer to this question but can't figure it out at the moment. I'm trying to workout what is the enthalpy condition in the suction line of an AC compressor to calculate isentropic efficiency. The condition i have is 2.5bar suction pressure at a...

Hi All, I have a question regarding using threaded steel inserts into an aluminum housing. If you have a steel threaded insert which is bolted into an aluminum housing from what i understand this is ok. However if you then want to tighten a bolt inside an internal thread within the steel...

Hi all, Does anyone know of any cast aluminum brackets that can have an aluminium insert pressed into them with an internal thread to tighten onto a fastener. This is for an extension to the bracket that cannot be accommodated by the casting The press force of the insert would have to be...

Hi all, I want to calculate the total hemispherical emissivity of a surface when the emissivity curve changes with wavelength (assume spectral emissivity does not change with temperature) I have seen examples in text books that show how to calculate emittance by integration on simple square...

Hi all, I'm looking for an empirical correlation or calculation that can be used for assessing convective heat transfer along a pipe but on the external surface not the internal surface. I know i can use the Gnielinski correlation for turbulent flow in an internal pipe. Is there an...

Hi all, I'm currently building a 2D heat transfer model in matlab of a pipe and want to account for the effect of different surface roughness on the external surface of the pipe in contact with external airflow at 90deg to the longitudinal axis of the pipe. I'm currently using Churchill...

Hi all, I'm currently creating a 1D thermal model for assessing steady state heat transfer across a hollow cylinder with and without thermal insulation on the cylinder. The heat flow path is from internal gas flow through to external surface temperature for the cylinder or the insulation...

Hi all, I'm currently designing a test rig to measure air temperature of an enclosure with a heat source coming from inside the enclosure, airflow will be measured just upstream of the enclosure with a pitot tube and a centrifugal airflow fan upstream of the pitot tube. On the outlet of the...

Hi, I’m looking to run a simple 1d model to determine the surface temperature of a component that is x distance away From a pipe with and air gap between them, the pipe is covered by thermal insulation. Up until now I have been using thermal conduction and radiation at the outer surface of the...