How do I find an enthelpy value if my temp. is below 50 deg. celcius?

In summary: Okay ill try it using the steam table.Thanks you sir, i really appreciate that. glad someone can help here
  • #1
bakharuddin
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I want to design a curding machine (Milk to Cheese) with an open system that operate at isobaric process (contant pressure),
P = 1 atm = 1,... bar
the range of temperature is = 25-75 0C
can i find an enthalpy of water from Mollier Diagram if my temp. is 25 to 75 degree celcius ? how ?

from my view, i must separates water properties from milk to make curds.
so i use mollier diagram but still confuse about it.

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  • #2
What is the heat capacity of water?
 
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  • #3
Chestermiller said:
What is the heat capacity of water?
the amount of heat needed to raise its temperature a certain amount. One of water's most significant properties is that it takes a lot of heat to it to make it get hot. Precisely, water has to absorb 4,184 Joules of heat for the temperature of one kilogram of water to increase 1 degree celsius (°C)
 
  • #4
bakharuddin said:
the amount of heat needed to raise its temperature a certain amount. One of water's most significant properties is that it takes a lot of heat to it to make it get hot. Precisely, water has to absorb 4,184 Joules of heat for the temperature of one kilogram of water to increase 1 degree celsius (°C)
So, why can't you use this to get the enthalpy of water at 50 C (consistent with the Mollier diagram reference state)?
 
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  • #5
Chestermiller said:
So, why can't you use this to get the enthalpy of water at 50 C (consistent with the Mollier diagram reference state)?

is there any equation to help me maybe ? still confuse to use this diagram :H
 
  • #6
bakharuddin said:
is there any equation to help me maybe ? still confuse to use this diagram :H
Why are you using a Mollier diagram? Why aren't you using the Steam Tables? The change in enthalpy with respect to temperature is $$\Delta H=mC_p\Delta t$$assuming no change of phase.
 
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  • #7
Chestermiller said:
Why are you using a Mollier diagram? Why aren't you using the Steam Tables? The change in enthalpy with respect to temperature is $$\Delta H=mC_p\Delta t$$assuming no change of phase.

because from mollier diagram there is an x value which is a moisture of water parameter, and i think is a must factor to include.
am i wrong ? or is it more simple using steam table to get the enthalpy ?
 
  • #8
bakharuddin said:
because from mollier diagram there is an x value which is a moisture of water parameter, and i think is a must factor to include.
am i wrong ? or is it more simple using steam table to get the enthalpy ?
The moisture parameter gives the fraction that’s vapor, but, in your case, you have purely a liquid stream, right? It is, of course, simpler to use the steam tables(or even the equation), and it’s more accurate than reading off a graph. You seem to need to review thetmo to get the basic concepts down pat.
 
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  • #9
Chestermiller said:
The moisture parameter gives the fraction that’s vapor, but, in your case, you have purely a liquid stream, right? It is, of course, simpler to use the steam tables(or even the equation), and it’s more accurate than reading off a graph. You seem to need to review thetmo to get the basic concepts down pat.

Okay ill try it using the steam table.
Thanks you sir, i really appreciate that. glad someone can help here :smile::smile::smile::smile::smile:
 
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1. How do I determine the enthalpy value if my temperature is below 50 degrees Celsius?

To find the enthalpy value when the temperature is below 50 degrees Celsius, you will need to use the enthalpy equation: H = Cp * (T2 - T1). Cp represents the specific heat capacity of the substance, T2 is the final temperature, and T1 is the initial temperature. By plugging in the known values, you can solve for the enthalpy value.

2. What is the significance of finding the enthalpy value?

The enthalpy value is a measure of the amount of heat energy in a substance. It is important in various industrial processes, such as determining the efficiency of a reaction or calculating the amount of energy needed for a reaction to occur.

3. Can I use a different enthalpy equation if my temperature is below 50 degrees Celsius?

Yes, there are alternative equations that can be used to calculate enthalpy at lower temperatures, such as the Clausius-Clapeyron equation. However, the specific heat capacity and temperature values may need to be adjusted accordingly.

4. What if my substance does not have a specific heat capacity listed for temperatures below 50 degrees Celsius?

If the specific heat capacity is not listed for the temperature range you need, you can use the average specific heat capacity for that substance. This value may not be as precise, but it can still provide a reasonable estimation of the enthalpy value.

5. Is it necessary to convert the temperature to Kelvin before finding the enthalpy value?

Yes, it is important to convert the temperature to Kelvin before using the enthalpy equation. This is because the equation requires the temperature to be in absolute units, and Kelvin is the standard unit for temperature in the scientific community.

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