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20-03-2011, 02:38 PM #1
Ice rink brine temperature? for ambient temperature above the ice surface +24°С
Hi, This is Aykut. I have a question about ice rink design.
Our Ice Rink Technical specification ;
-size of the ice rink; 806m2
-ambient temperature above the ice surface;+24°С
- relative humidity above the ice surface;50%
- air velocity above the ice surface;0,2m/sec
- ice thickness;40mm
- required cooling capacity;≈280kW
Refrigerant;R-404A
Outdoor Temperature;+40°С
We have two offer and two different disegn;
First offer;
Semi hermetic screw compressors (2+1) 1pcs.
- type Bitzer or similar
- cooling capacity 291,0kW
- evaporating temperature -17°С
- condensing temperature +50°С
- power consumption 224,0kW
Pipe & tube heat exchanger 1pcs.
- type Alfa-Laval or similar
- capacity 460,0kW
- evaporating temperature -17°С
- glycol inlet temperature -9°С
- glycol outlet temperature -12°С
number of circuits 3pcs
Second offer;
Semi hermetic screw compressors (3+1) 1pcs.
- type Bitzer or similar
- cooling capacity 282,0kW
- evaporating temperature -22°С
- condensing temperature +50°С
- power consumption 200,0kW
Pipe & tube heat exchanger 1pcs.
- type Alfa-Laval or similar
- capacity 320,0kW
- evaporating temperature -22°С
- glycol inlet temperature -14°С
- glycol outlet temperature -17°С
Which glycol inlet&outlet temperature true? (-9°С /-12°С or -14°С /-17°С)
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21-03-2011, 05:51 AM #2
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Re: Ice rink brine temperature? for ambient temperature above the ice surface +24°С
first one better than second one
less compressor - more capacity in heat exchanger but ask them to reduce his design to -14°С /-17°С to get
better ice and hard ice with less time during ice up time.look like they have to change model of compressor
you asked . Which glycol inlet&outlet temperature true? (-9°С /-12°С or -14°С /-17°С)
both is true only design is different and delta T is same (3)
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24-03-2011, 06:40 AM #3
Re: Ice rink brine temperature? for ambient temperature above the ice surface +24°С
thanks for answer but i have doubt about ice temprerature for ambient +24°С
if glycol inlet&outlet temperature -9°С /-12°С then ice temperature will be +1,16°С
if glycol inlet&outlet temperature -14°С /-17°С then ice temperature will be -4С(it s true)
according to ice temperature formulas;
tm = ta – ((ta – ti) / Θ))
• tm – cooling medium temperature (°C); (glycol outlet temperature)
• ta – ambient air temperature (°C);
• ti – ice temperature (°C);
• Θ – ice layer relative (it is only coefficient)
Θ=2•π•λc/(ε•α•ln((2•ε)/(π•d)•sh(2•π•(h+λc/α)/ε)))
• ε – distance between pipe loops (m);
• α – heat-transfer factor W/m2•K;
• h – equivalent heat resistance layer;
• d – pipe diameter (m);
• λc - concrete heat conductivity (W/m•K).
• sh – hyper sinus
α=(Q-q)/(ta-ti)
• Q – total heat load (kW);
• q – heat load through the ground (kW).
h=d/2+δc+δi•(λc/λi)
• δc – concrete layer thickness above the pipe loops (m);
• δi – ice layer thickness (m);
• λi - ice heat conductivity (W/m•K).
• ta = +24°C, customer request;
• ti = - 4°C, customer request;
• ε = 0.08m, ice rink standard solution;
• d = 0.025m, ice rink standard solution;
• λc = 1.75W/m•K, physical properties tables;
• λi = 2.21W/m•K, physical properties tables;
• Q = 264.64kW, taken from HUURRE calculation;
• q = 6.53kW. not mentioned in HUURRE calculation so i use 8.1W/m2;
• δc = 0.032m, ice rink standard solution;
• δi = 0.04m, customer request.
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26-03-2011, 06:02 PM #4
Re: Ice rink brine temperature? for ambient temperature above the ice surface +24°С
one question, why haven you you used method of heat resistances with heat source? And coudl you tell me where have you found this formula? could you post a link or anything else which will give a bit better understanding of physics behind.
BR
MilosBogBe careful about reading health books. You may die of a misprint.