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The last few weeks have been a bit full on with work and home, and I found myself falling behind a bit on the course. This is week 3 just past, with week 1 and 2 being on process balance problems - mass, molar, and volume. I'd found the single process equations in week one fairly easy, and had extrapolated that to the multi process equations as not being too difficult either. I got really bogged down though in some of the maths, and made some silly mistakes misreading my own handwriting on the maths! I did spent some solid time on this yesterday though and think I'm there, but it shook my confidence a bit.

Week 3 is static fluid pressures, with many applications of ρgh ie density x gravity x height to give the static pressure due to a height of fluid, along with formulae for calculating balanced pressures in U shaped manometers. I had serious brain ache the first time around reading it, but after making dinner, watching a bit of TV and coming back to it last night, I'm a wee bit more comfortable with it.

Still.. the multi process problems did swallow time yesterday like a black hole, and that worries me a bit as I didn't finish the extra questions for the week. It still feels a bit lonely doing this at a distance, though to be fair all I've done last week is worked, cooked, ate , and slept - genuinely. I'm two staff down just now and it's almost impossible to recruit at the moment, there's just so few doctors available. Anyone out there who is a doctor with public health or national experience - please pm me!

A x
 
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This week we've been given our first assignment for introduction to process control which is worth 30% of the mark for the course. I'm a bit disconcerted as it seems a bit too easy, ie easier than a lot of the example questions we've been working through week to week. The biggest hassle has been getting MS Word to format equations correctly, it seems awfully fiddly to type it all up, far longer than it takes on paper. Anyway, I now need to read up on this week's work as well which is about pressure loss over valves I think.
 
Process control theory is utterly harrowing. I did it just to HNC level at college as part of my apprenticeship and quite frankly, had to cheat quite extensively to get the required pass marks. I have then spent the subsequent 20 years working exclusively in the field of process control, where I have applied precisely nothing of what I did at college.

Such is the world of academia I suppose.

That said, I am glad our doctors take the time to acquire some underpinning knowledge......
 
MS Word is a pain for formatting equations. Also a pain if (when) you have to change something later that affects all the following calculations. Maths software is better if it's something you'll be doing a lot, even if you then have to copy and paste it back into Word. I use Mathcad, it's a bit quirky but after a while becomes natural. I'd expect the uni would have floating licenses for something? Maybe there's a more specific one for chemistry /biology
 
Jim Brewster said:
MS Word is a pain for formatting equations. Also a pain if (when) you have to change something later that affects all the following calculations. Maths software is better if it's something you'll be doing a lot, even if you then have to copy and paste it back into Word. I use Mathcad, it's a bit quirky but after a while becomes natural. I'd expect the uni would have floating licenses for something? Maybe there's a more specific one for chemistry /biology
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Thanks for the pointer. I think this current module is the main one needing lots of algebraic expression so I'll keep working with Word for now but will look at Mathcad in more detail if there are more modules like this.

@the baron I did find a mistake after I'd submitted it so had to resubmit the file! I'd labelled all the mass flow rates as M1 to M6 Forgetting that 'M' is for Molar flow rates rather than 'G' for mass flow rates. It wasn't a big thing to change but it was a salutary reminder to check and recheck my work.
 
I got a bit behind with other work commitments but am almost up to date now. Just finished the modules for week 7 on process control and this is getting into proper brain stretching industrial processes. Continuous heating of basic continuous flow processes... eek. I haven't had the time I'd have like to spend on working at the example questions so this is now pushing me a bit... like really quite a bit.

This includes concepts such as Latent heat of vaporization: heat required to convert 1kg of liquid to 1kg of gas (e.g.water to steam), differences in heat flow equations with sensible heating (no phase change) and latent heating (phase change),

The last example question is a bit hard - I'm going to reread this tomorrow as this is way out of my medical field!
•A continuous flow steam generator consists of a pipe containing water with a flowrate of 0.012 kg/s and a pressure of 1 bar. An electrical heating element surrounds the pipe and is rated at 30kW. What is the minimum water inlet temperature, which will result in fully vaporised steam exiting the generator?
•Assume:
•cp = 4.2kJ/kgK
•hfg = 2258kJ/kg
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Is it something like..
*(1 bar approx atmospheric pressure)
*1 bar boiling point = 99.6C
*Assume steam is also at 1 bar
*Assume all the element's heat goes to the water

Energy input per second = 30
Energy per second required = 0.012 X (2258 + 4.2(99.6-T))
so T = (30/0.012 - 2258 - 418.3)/-4.2
T(min) = 42C
 
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Jim Brewster said:
Is it something like..
*(1 bar approx atmospheric pressure)
*1 bar boiling point = 99.6C
*Assume steam is also at 1 bar
*Assume all the element's heat goes to the water

Energy input per second = 30
Energy per second required = 0.012 X (2258 + 4.2(99.6-T))
so T = (30/0.012 - 2258 - 418.3)/-4.2
T(min) = 42C
Click to expand...
Which makes it look sooo simple 😆
I suspect your answer might be more accurate than the worked example given as it takes the boiling/saturation temperature of water as 100 deg.
Interestingly your calculation kept the Kilo prefix for the units, whereas I converted the values all to SI units - but you got the same answer, which is interesting in itself. Thanks genuinely for this, it's helped me understand this a lot better!
 
As someone who no longer goes out to work, keeps the house free from infestations of children (in spite of Mrs R’s attempts of letting little people into the house) and cooks less than 50% of the meals, I’m feeling very guilty about my lack of effort/progress with respect to learning a new language after reading your progress.
I really must do better. Full of admiration, keep it up 😀
 
Loving this! Thermodynamics, Heat Transfer and Fluid Dynamics were some of my best courses in uni. Been over 20 years since I had to actually do the calculations by hand, in real life, (Engineering software is amazing). but I think the cobwebs could be shaken out if I needed to.
 
Serious brain ache from working through this week's course on conductive and convective heat loss, including such gems as multiple slab conductive losses, and thermal resistance for pipes with insulation on them...
Screenshot 2022-11-06 at 14.23.46.png


Oh and then on to the Dittus-Boelter correlation for estimating the Nusselt Number used to characterise the heat transfer coefficient 🙈 . This last part on dimensionless numbers to calculate film heat transfer coefficients is something I'm going to need to go over a couple more times. This is apparently one of the hardest required modules for bioscience people like myself, I really really hope so.
 
Brain dead this weekend. Still on question 1oif the final assessment (2 questions) I had to recalculate the mass balances twice as I realised I’d got it completely wrong the first time. It’s a question about the energy requirements for a two stage still. I’d worked on the basis of a residual 0.1 ABV for the pot ale (waste from the wash still) but realised only at the end when lots of things didn’t balance, that the question was using an idealised extraction of all the alcohol from the wash …, AGGHHH ! this is consuming time like a black hole, I’ve breached the event horizon and time doesn’t feel like it has any meaning any more.
I know this was supposed to be the hard module for bioscience people such as myself but ouch this is really hard.
I don’t suppose anyone knows the typical mass of copper for a pot still in a commercial brewery - ideally with a reference??!!

Anna
 

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