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aminem666
06-04-2016, 07:49 AM
Hello everyone!*

I am just about to take part in a refrigeration system design competition but unfortunately it is my very first time stepping in the real world of engineering & I do not know exactly what are the steps of designing a one-stage vapor compression refrigeration cycle. The system I should design must be able to handle the followings:

1-cooling down a 50 L of water storage for 28 C to 7 C at a minimum time duration.

2- Constraint: compressor power must not exceed 600 W! **

I would deeply*appreciate you if you could help me through.

Rob White
06-04-2016, 04:54 PM
Hello everyone!*

I am just about to take part in a refrigeration system design competition but unfortunately it is my very first time stepping in the real world of engineering & I do not know exactly what are the steps of designing a one-stage vapor compression refrigeration cycle. The system I should design must be able to handle the followings:

1-cooling down a 50 L of water storage for 28 C to 7 C at a minimum time duration.

2- Constraint: compressor power must not exceed 600 W! **

I would deeply*appreciate you if you could help me through.

Wow welcome aboard with your first post and question.
You are entering a competition in something you know nothing about?

Sounds like a proper challenge :D

It would help if you knew what you were doing but I'll start with a few pointers
because if this is your task I don't want to give you all the answers.

Single stage compression tends to be with one compressor and vapour
compression is how the comp work. So a one-stage vapour compression refrigeration cycle is a
normal fridge system with 1 evaporator, 1 compressor, 1 condenser and 1 expansion device.

50l of water is 50kg of water, so that is your work load and you are reducing
it from 28C to 7C, that is a Delta T of 21 C (temperature of 21 C).

You need to find out how much heat per deg C is in 1kg of water and then X (times) that
by 50, that will give you how much heat you need to remove in total. You have a max
of 600 W to do this with so your calculations will lead to a system designed around 600 W
that has to remove X amount of heat from 50kg of water.

Simples................................ :D

Start with basics.

How much heat does it take to change 1kg of water by 1 C???????

Find that out and come back and we will take it further.

But we can't do the work for you, that would be cheating.

:)

Rob

.

Magoo
07-04-2016, 06:04 AM
a bit of a hint.
water.,
1 litre equals 1 kg on average at temps you are quoting.
sensible heat factor for chilling water is 4.186 kj / kg/ 'K

mikeref
07-04-2016, 10:00 AM
I can see some-one spending all their spare time reading the Basics of Refrigeration. Understanding what you read could take some time and Patience.

Just as well you don't have to build a working model. Looks like Rob is willing to guide you through the process.
There are numerous calculations and Formula that have to be used.

Since Magoo has offered the specific heat of water, i will add something relevant to your project. Which refrigerant will you use?... 600 Watt compressor is your limit. You will have to choose a Sealed compressor that won't stall under load.