Complex Thermo-Dynamic System of Equations

Click For Summary
SUMMARY

The discussion focuses on designing a water-cooling system for a PC using thermodynamic principles. The user aims to calculate the average temperature of the liquid in a closed-loop system that includes a mini-fridge and an air conditioning unit. Key variables identified include the BTU ratings of the mini-fridge (330 BTU) and air conditioning unit (5200 BTU), the heat output of the AMD Phenom II x4 965 CPU (approximately 125 Watts), and factors such as fluid speed, ambient temperature, and thermal capacity of water. The user seeks guidance on further calculations and system efficiency to ensure optimal performance without damaging the components.

PREREQUISITES
  • Understanding of thermodynamic principles, including heat transfer and fluid dynamics.
  • Familiarity with BTU and wattage conversions for cooling systems.
  • Basic knowledge of PC cooling components and their thermal characteristics.
  • Ability to perform calculations involving heat dissipation and thermal capacity.
NEXT STEPS
  • Research the principles of heat transfer, specifically conduction and convection, in closed systems.
  • Learn about calculating thermal efficiency in cooling systems, focusing on BTU ratings and heat exchange.
  • Investigate fluid dynamics to understand the impact of flow rate and friction on heat absorption.
  • Explore the use of simulation tools for modeling thermodynamic systems to predict performance outcomes.
USEFUL FOR

This discussion is beneficial for PC builders, thermal engineers, and hobbyists interested in custom cooling solutions, particularly those integrating refrigeration technology into computer systems.

FriedSushi87
Messages
3
Reaction score
0
I took AP Physics (failed) back in high-school, and I've retained most of the information, but we didn't delve too far into thermo-dynamics, instead focusing mostly on resistance, acceleration, velocity, friction, ect...

I am trying to calculate a few things to determine the average temperature of a liquid in a system after the system is in motion...

What I'm doing is trying to calculate and work this system out before I build it. I'm going to water-cool my PC. I am going to put the reservoir inside of a mini-fridge, and the radiator(s) in front of an Air Conditioning unit. Everything connected together by tubes to create a closed system loop.

[PLAIN]http://www.zombiefire.com/ocn/crazyidea.png

Since I'm not that knowledgeable about thermodynamics I did a bit of research before I started and began to determine my variables.

1) BTU of mini-fridge
2) Heat Given off by CPU
3) BTU of A/C unit.
4) Initial temperature of water
5) Rate of dissipation of heat from a Radiator. (cooled by A/C). Obviously you won't have 100% efficiency and have all 5000 BTU of the A/C into the Radiator...
6) Amount of liquid in the loop. (resevoir + tubing + Radiator)
7) Ambient air temperature. (outside the system)
8) Speed of fluid pumped through system (effecting heat absorption)
9) Friction of fluid through system (increasing heat)
10) Thermal capacity of water.

I'm not sure if I've forgotten any variables...

I then tried to teach myself some basic thermo-dynamics and get some of the variables from around the internet:
A/C 5200 BTU = (~~1500 Watts)
AMD Phenom II x4 965 CPU ~~ 125 Watts (more if overclocked?)
Mini-Fridge = 330 BTU?

A large mini fridge (3.2 cu ft) has a surface area of around 1.85 meters squared. Its walls are made of 1" styrofoam, with a metal or plastic casing. Assuming there is free convection on all surfaces of the fridge, and the fridge is at 4 degrees C in a 22 degree C room, the heat transfer out of the fridge is around 20 watts. (this value is probably a little high, I haven't counted a lot of the smaller thermal resistances)

1 ton of refrigeration is the rate of heat removal required to freeze a short ton (i.e., 2000 pounds) of water at 32 °F in 24 hours. Based on the heat of fusion for water being 144 Btu per pound, 1 ton of refrigeration = 12,000 Btu/h = 12,660 kJ/h = 3.517 kW++

Now for this system to work correctly, the temp. of the fluid in the system has to be at or below a certain temperature (the Fridge isn't made to be on 100% of the time, but instead is meant to cycle on and off. I don't want to burn out the fridge).

I'm not really sure where to go from here. If anyone could get me started, give me some pointers and point me towards the right direction?
 
Last edited by a moderator:
Science news on Phys.org
Ha=(Hw)-(Hcpu)+(Er * Ha)+(Hf)

Ha=Average Heat
Hw=Heat of Water (initial)
Hcpu=Heat of CPU/hr
Er=Heat of AC>Radiator system
Ha=Heat of AC/hr
Hf=Heat of Fridge/hr

?
 
Is there no-one here who can help me?
 

Similar threads

I have a few questions about refrigeration and AC units
  • · Replies 1 ·
Replies
1
Views
3K
Graduate Heat exchange in a thermal storage based on phase change materials
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Thermo: Calculating the temperature drop from gas leaving a system
  • · Replies 11 ·
Replies
11
Views
10K
Undergrad Building a Vacuum Filling System: Valves & Fine Leaks
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Calculating Heat Transfer Between 3 Mediums: Copper, Ground, Water
  • · Replies 4 ·
Replies
4
Views
2K
High School How does sweating cool a person down?
  • · Replies 9 ·
Replies
9
Views
15K
Undergrad Need help in solving thermo problem
  • · Replies 2 ·
Replies
2
Views
2K
Could we make a practical solar fridge?
  • · Replies 30 ·
2
Replies
30
Views
4K
Zeroth Law of Thermodynamics
  • · Replies 5 ·
Replies
5
Views
2K
Heat Transfer Through a Two Material System due to a Light Source
  • · Replies 10 ·
Replies
10
Views
3K