Heat Transfer Calculations
Heat Transfer Calculations
(OP)
Hello,
I work with a vessel manufacturers and we are frequently asked by customers to perform heat transfer calculations.(i.e. if the vessel you are making us has 500Lt of water in it @ X°C, how long will it take to either heat it up or cool it down or how much energy (W or kW) is needed to heat it, etc.)
I was wondering if someone had a set of hand-written calculations that I could possibly work with? Or some advice on where to get an example that I could use again.
The vessels are usually stainless or an exotic alloy with dimple, limpet or flooded jacket and usually have agitators.
I know this is a big ask but I would appreciate it.
Many thanks in advance,
dhill11
I work with a vessel manufacturers and we are frequently asked by customers to perform heat transfer calculations.(i.e. if the vessel you are making us has 500Lt of water in it @ X°C, how long will it take to either heat it up or cool it down or how much energy (W or kW) is needed to heat it, etc.)
I was wondering if someone had a set of hand-written calculations that I could possibly work with? Or some advice on where to get an example that I could use again.
The vessels are usually stainless or an exotic alloy with dimple, limpet or flooded jacket and usually have agitators.
I know this is a big ask but I would appreciate it.
Many thanks in advance,
dhill11





RE: Heat Transfer Calculations
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize
RE: Heat Transfer Calculations
We would normally get the help of a third party, or the customers engineering house would do the calculations on their behalf.
The engineering house might just ask us what is the jacketed area on the vessel or stipulate that the vessel needs so many m2 of jacket.
The company I work for is not particularly large so trials have never been done.
RE: Heat Transfer Calculations
a) heating the liquid [sic]
b) once the liquid is warmer than the ambient - compensate for heat loss from outside wal to ambient
c) if the vessels are open or vented - evaporation
a) Should be simple enough (dT*Cp*vol*density) - thats the result in kJ - and then your client must tell you the time for heating, divide by time in seconds and you have the effect in kW
b) More complicated - but unless is MUCH hotter (or heating is very slow) it wont be that much compared to the energy required for heating.
c) Could be a significant amount - have no clue right now
b) will depend on geometry and ambient condition (exposure to wind etc).
Best regards
Morten
RE: Heat Transfer Calculations
RE: Heat Transfer Calculations
RE: Heat Transfer Calculations
There was an engineer who had an exceptional gift for fixing all things mechanical. After serving his company loyally for more than 30 years, he happily retired.
Several years later the company contacted him regarding a seemingly impossible problem they were having with one of their multi-million dollar machines. They had tried everything and everyone else to get the machine fixed, but to no avail. In desperation, they called on the retired engineer who had solved so many of their problems in the past.
The engineer reluctantly took the challenge. He spent a day studying the huge machine. At the end of the day, he marked a small "x" in chalk on a particular component of the machine and proudly stated, "This is where your problem is." The part was replaced and the machine worked perfectly again.
The company received a bill for $50,000 from the engineer for his service. They demanded an itemized accounting of his charges. The engineer responded briefly:
One chalk mark -$1
Knowing where to put it $49,999
It was paid in full and the engineer retired again in peace.
RE: Heat Transfer Calculations
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize
RE: Heat Transfer Calculations
RE: Heat Transfer Calculations
http://w
RE: Heat Transfer Calculations
And, heed the advice in posts before mine.
RE: Heat Transfer Calculations
dhill11
RE: Heat Transfer Calculations
You will need to know the mass of water, the heat input in BTU/s or Watts..
You will need to know, roughly, the surface area exposed to the water where the heat input is being generated (heating coils? I dont know what you use). You will need to assume some things like convection coefficient which will vary with time.
You may not be able to get away with lumped capacitance method because water is a poor conductor of heat and will not change in temperature uniformly. Look up on the internet for lumped capacitance and you will see why.
Getting your heat transfer coefficient will be the challenging part because it depends on fluid motion due to natural convection (I am assuming you dont have an agitator in there somewhere). Anyway as others have said, the calculations can be performed but there is not ONE equation that will do it. You need to make assumptions and this is where experience and judgement comes into play.