Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Control components for DHW preparation by heat exchanger
M.Sc. Jan Eric ThorsenApplication Center
Danfoss A/S District Heating Controls
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Example multifunctional controller
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Why multifunctional controller ?
•One controller•Space savings•Reduced assembly costs•Flexible functionality
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
The ”optimum” control conceptdepends on:
• Primary supply condition• Demand to control performance• Demand to functionalities
T
DH DHW
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Primary supply conditions
Q1 ; T11 = 60-100°C T
T22 = 45 - 55°C
Q2 = 0-0,2 l/s ; T21 = 10°C
dP = 0.5 to 6 bar
T12 = 15-25°C
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
C o n s t a n t p e r m a n e n t d e v i a t i o n f r o m s e tp o i n t a f t e r a t e m p e r a t u r e c h a n g e , + / - 2 K
M a x i m u m p e r m a n e n t t e m p e r a t u r eo s c i l l a t i o n s , + / - 2 K
M a x i m u m t e m p e r a t u r e d e v i a t i o n a f t e r am o m e n t a r y l o a d c h a n g e , 1 0 K
T r a n s i e n t t i m e a f t e r a l o a d c h a n g e < + / - 2 K w i t h i n 1 2 0 s e c
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Functionalities /Control performance
•Idle temperature (at no DHW tapping)
•DHW Circulation
•Priority function DHW/Heating
Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Q2
TQ1
Thermostaticcontroller
Proportionalflow controller
Basic control components
Differential Pressurecontroller
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Q2
Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Thermostaticcontroller
Q2
TQ1
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Thermostaticcontroller
Q2
TQ1
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Proportionalflow controller
PM controller
11
Q2
Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Proportional flow controllerwith a temperature controllerserial connected
PTC controller
11
T
Q2
Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
DCW
DHW
Heatingflow
Heatingreturn
T
DH Flow
DH Return
Temperature controller parallel connected with proportional controller plus dP controller
AVTIController
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Example AVTI controller
Danfoss AVTI valve, dP station = 4.0 bar, T11 = 90°C
0
10
20
30
40
50
60
70
80
0 2 4 6 8 10 12 14 16 18 20 22 24 26
time [min]
Tem
p [
°C]
0
100
200
300
400
500
600
700
800
Flo
w [
l/h]
T22 Q2 Q1
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
TT
T
Heatingreturn
Heatingflow
Combined therm. and prop. control (reduced stand by temp.)
Therm. control with reduced stand by temperature control and DHW priority
Other combinations
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Thermostatic variants
T
Therm. controller with “special” position of sensor
T
Therm. controller with “Heat Bridge”
AVTB with GeminaHeat bridge
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Recommendations:
• constant dP and T11, or accept seasonal adjusting• ”free” setting of stand-by temperature
- (additional thermostatic controller)• Preventing high temperature peaks
- (preventing lime scale deposits)
• variable dP and T11
• comfort of high standby temperature
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Proportional controller:
Thermostatic controller:
Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Recommendations:
Serial coupling:
Parallel coupling:
• variable T11, variable dP• control performance• ”free” setting of stand-by temperature
- (additional thermostatic controller)
• variable T11, but constant dP• control performance• comfort of high standby temperature
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Euroheat & Power, 2. RTD Workshop, High Efficiency – Improved Building Installations and Customer Comfort, Brussels 2-3 February 2006
Trend within compact DHW/H sub stations:
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• Towards compact multifunctional controllers
• Fulfilling specific demands > flexibility