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Temperature Operational temperature n n Design temperature t2t2 t1t1 t w1 t w2 t Tp,max twtw Temperature difference - emitter = t w1 - t w2 Temperature.

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Presentation on theme: "Temperature Operational temperature n n Design temperature t2t2 t1t1 t w1 t w2 t Tp,max twtw Temperature difference - emitter = t w1 - t w2 Temperature."— Presentation transcript:

1 Temperature Operational temperature n n Design temperature t2t2 t1t1 t w1 t w2 t Tp,max twtw Temperature difference - emitter = t w1 - t w2 Temperature difference system = t 1 - t 2 System supply t 1 Systém return t 2 Emitter supply t w1 Emitter return t w2 Maximal emitter surface temperature t Tp max Mean emitter temperature tw

2 Temperature in the system n Heat transferred by the system n Heat transferred by the emitter t2t2 t1t1 t w1 t w2 t p1,max twtw

3 Temperatures Design Criterions   Economical criterions   Physical properties of the medium   Hygiene requirements   Technical properties of the heat source

4 Temperature Parameters design n Heating system supply temperature   Low- temperature t 1 <=65°C   Medium - temperature 65°C 115°C n Temperature difference – –10K - 25K, high temperature 40K - 50K. – –90/70 °C, 80/60°C, 75/55°C, 55/45°C

5 Temperature Parameters Design n Emitter –Maximal surface temperature ( °C) –Temperature difference n Two-pipe = system temperature difference ( K) n one-pipe < system temperature difference OS ( K)

6 Piping materials –The material should be selected at the beginning of the design process –Used materials n steel n copper n plastic

7 Piping materials Steel n Traditional material n Welding

8 Piping material Copper n Lower material usage n Chemical reaction with water pH min7 n Electrochemical corrosion (Al) soldering, torch brazing soldering, torch brazing

9 Piping material Plastic  Materials   Netted polyethylene (PEX, VPE),   polybuten (polybutylen, polybuten-1,PB),   polypropylen (PP-R, PP-RC,PP-3),   Chlorided PVC (C-PVC, PVC-C)   Multilayer pipes with metal n Life-cycle !!! n Oxygen barierre ?

10 Piping material - Plastic

11 Heating system hydraulic calculation

12 Calculation n Temp difference setup n Transferred output n Circulation mode n Hydraulic scheme, sections, circuits n Water flow rate

13 Design of the pipe diameter n Forced circulation –method economical specific pressure loss Pa.m -1 –method optimal velocity n 0,05 - 1,0 m.s -1 (!!! Noise) –method given pressure difference buoyancy + pump head buoyancy + pump head n kPa Natural circulation Natural circulation – method given pressure difference buoyancy buoyancy

14 Pressure loss calculation n Pressure loss –friction –Local resistance n Pressure loss of the circuit compare with the pump head n Pressure excess is reduced by the control valves n Pressure lack – must be changed the pump or redesigned the system


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