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Refrigeration systems can be inefficient in many ways. Whether at concept stage, application stage or "The afterlife", things can go wildly wrong and yet life seems okay- the cold store will be cold. Hey who bothers to check if their system is drawing 50% more electricity than optimum? Thsi short slide deck gives some insight into where it can go wrong. It was presented ion the 25th August 2011 voa webcast through the 2Degress Network (great guys).So who needs to review this? The engineering team perhaps but ideally show it to the Chief Financial Officer in your oganisation. He's the guy paying the bills!
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What to look for in efficient system design
Dave Pearson
Director of InnovationStar Refrigeration
or….
What to look for inefficient system design
Dave Pearson
Director of InnovationStar Refrigeration
Where
What your “Expert” advisors
should be telling you they are focusing on
Dave Pearson
Director of InnovationStar Refrigeration
Star Refrigeration
Largest in UK
Est. 1970300+
employees
Star Refrigeration
Totalsolution
Solutions
You
Engineering cost
Lifecycle cost
Solution
Solutions
Capital
Operating
Maintenance
Clients
Awards
Efficient System Design
Temperature LiftEvaporator Design…... and OperationCondenser Design…... and OperationPart load operationAuxiliary power consumersChoice of refrigerant
3 areas of MUDA or waste
Theory ApplicationThe
After-Life!
Basic Efficiency - Various Cycles
Ammonia’s Critical Point
Mollier Diagram - Ammonia
0.01
0.1
1
10
100
-200 0 200 400 600 800 1000 1200 1400 1600
Enthalpy (kJ/kg)
Pre
ss
ure
(M
Pa
)
Critical Point: 11.3MPa 132oC
Ammonia’s Critical Point
Basic Efficiency - Various Cycles
** Simple selections, uneconomised
28% improvement
49% improvement
R404 -20 Te/30C Tc vs
R717 -10 Te/20T Tc
= 118% better
Why are refrigerants different?
Application- a chilled building loop
Even the best designed system can be badly applied…….
Imagine a chiller (1000kW) on a 12C/6C circuit.Spring time, lower comfort load, say 500kW
Option a) fit inverters to the glycol circuit, save50% of 15kW = 7.5kW
Option b) float the delivery temperature from 6C up to 9C. Save 3x3% = 9% of 125kW = 11.25kW
Perhaps the return temp could float too?
Application- “Don’t waste your waste”
Imagine a chiller (1000kW) on a 12C/6C circuit.Nearby a boiler delivering steam from water.
Chiller will reject circa 1300kW at 40CBoiler will consume 1300kW to heat 3kg/s from 0C to 100C = £39/hr = £341k per 24/7 annum.
If the chiller heated the water to 40C this would save £136k per annum.
If the chiller heated the water to 80C this would save £278k per annum but cost additional £59k
Consider the whole energy equation and be bold.
Maintenance- a theoretical system (play video)
Click here for Starcare Optimising Operation Video on Youtube
Wrap up
Always take a step back, and consider the whole picture
Delegate responsibility to an expert BUT don’t abdicate.unless the expert is paying your electricity bill!
Be rigorous in the application of efficiency principles……and ruthless in the elimination of bad practices
How warm can the flow be? Every 1K = 3%How cool can the heat rejection be? Every 1K = 3%
How easy will the kit be to maintain? Maintenance pays!
Be prepared to pay if necessary…… but often, “good practice” is a no-cost option!!
