1/51 7 Heat pumps sizing

Transcription

1 1/51 7 Heat pumps sizing heat pump characteristics testing & operation conditions balance point storage size hydraulics

2 Heat pump 2/51 Q k rejected heat Q k P el Q v sink side P el COP Q P k el Q v Q k P el source side Q v Q k 1 1 COP Q v extracted heat

3 Heat pumps: ground source (borehole) 3/51

4 Heat pumps: ground source (ground HX) 4/51

5 Heat pumps: water source (water well) 5/51

6 Heat pumps: air source (ambient) 6/51

7 Types of heat pumps on the market 7/51

8 The trend is air source 8/51

9 ... also sanitary hot water HP increase 9/51

10 Heat pumps market in Europe 10/51

11 Top ten countries is the market 11/51

12 Heat pump parameters 12/51 heat output, heat capacity Q k [kw] heat output from condenser coefficient of performance COP [-] at given boundary conditions - t v1 and - t k2 - electric power P el [kw] t v1 t k2 - evaporator input = source output Q v [kw]

13 13/ C 5 6 COP [-] Air-water heat pump characteristics air-water air-water 35 C 50 C 4 Q k, P el [kw] 4 t k2 50 C e t [-] 3 50 C 2 2 t k2 35 C t v1 [ C] t v1 [ C]

14 electric power, heating capacity [kw] Air-water heat pump characteristics 14/51 conden.output temperature ambient air temperature

15 COP [-] Air-water heat pump characteristics 15/51 ambient air temperature

16 16/ C 5 COP [-] Brine-water heat pump (ground source) brine-water 35 C brine-water 50 C 8 Q k, P el [kw] 6 4 t k2 e t [-] 4 50 C 2 50 C 35 C 3 t k t v1 [ C] t v1 [ C]

17 heating capacity [kw] Brine-water heat pump (ground source) 17/51 conden.output temperature source temperature

18 heating capacity [kw] Water-water heat pump 18/51 conden.output temperature source temperature

19 Testing of heat pumps 19/51 EN Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling. EN : dtto - Terms and definitions EN : dtto - Test conditions EN : dtto Test methods EN : dtto - Requirements EN Heat pumps with electrically driven compressors. Testing and requirements for marking of domestic hot water units

20 Testing conditions 20/51 EN 14511: water-water W/W (W10 / W35) nominal: 10/35 C 10/45 C operation: 15/45 C 10/55 C EN 14511: brine-water (ground-water) B/W (B0 / W35) nominal: 0/35 C 0/45 C operation: 5/35 C 5/45 C 0/55 C -5/45 C EN 14511: air-water (ambient air) A/W (A2 / W35) nominal: 7/35 C 7/45 C operation: 2/35 C 2/45 C 7/55 C -7/35 C -7/45 C -7/55 C -15/35 C -15/45 C

21 Requirements on heat pump 21/51 Quality label EHPA (European Heat Pump Association) minimum COP from testing according to EN in respected lab brine-water B0/W35 COP > 4.3 water-water W10/W35 COP > 5.1 air-water A2/W35 COP > 3.1 declaration of sound power level documentation: planning, service and operation guides in local language customer service network, 24 h reaction time on customer complaints 2 years full warranty, spare parts inventory available for 10 years in stock 21/26

22 Seasonal performance factor 22/51 hot water space heating heat pump COP back-up Q HP SPF Q sh,hw COP Q Q HP el,hp SPF Q Q sh,hw el,tot Q el,hp Q el,aux Q el,bu Q el,tot

23 RES directive, minimum SPF 23/51 heat pumps consume electric energy produced mainly from fossil fuels (primary non-renewable energy source) SPF 1 1,15 h e h e electricity production efficiency european average 45.5 % SPF > 2.5 if SPF < better to use fossil fuels directly by combustion

24 EN Annex C (informative) 24/51

25 Operation modes 25/51 monovalent operation only heating device HP monovalent parallel bivalent operation under bivalent temperature (balance point) back-up heater is switched-on low temperature systems BU HP bivalent parallel

26 Operation modes 26/51 alternatively bivalent operation bivalent alternative under bivalent temperature back-up replaced heat pump. for high temperature heating systems BU HP the balance point = temperature under which the back-up heater is required

27 Operation modes 27/51 monoenergetic operation e.g. bivalent operation of electric heat pump with electroboiler (integrated in one device) balance point according to heat output (dimensioning) acc. heating water temperature sufficient heat output from heat pump high temperatures of heating water needed, which couldnt be supplied by heat pump, esp. in extreme winter

28 Heat pump sizing 28/51 determination of heat pump type available heat source determination of (condenser) heat output Q k (for space heating) building heat loss heat output for hot water design flow temperature design source temperature

29 flow temperature [ C] Teplota přívodní vody [ C] Balance point according to temperature 29/ radiators example of air source HP max output temperature 90/70 C 75/55 C 60/45 C 55/40 C 45/35 C 35/30 C underfloor heating Venkovní teplota [ C] outdoor temperature [ C]

30 Balance point according to heat output 30/51 30 heat output Q k [kw], heat load Q l [kw] Q 25 L, des ground source HP Q 20 L 15 Q k 10 5 balance point output temperature 35 C output temperature 50 C heat load ambient temperature t e [ C]

31 Balance point according to heat output 31/51 30 heat output Q k [kw], heat load Q l [kw] Q 25 L, des air source HP 20 Q L 15 Q k 10 5 Q k,bal balance point output temperature 35 C output temperature 50 C heat load ambient temperature t e [ C]

32 Balance point determination 32/51 design heat load Q L,des calculation according to EN for design external temperature (e.g. -12 C, -15 C, -18 C in CZ ) heat output at balance point Q k = Q L e.g. from desired fraction 60 to 100 % Q k,bal / Q L,des 30 t t t t i Q L, des e, des i Q L e t i Q k, bal t e, bal heat output Q k [kw], heat load Q l [kw] output temperature 35 C output temperature 50 C heat load Q k, bal t e, bal ti ti te, des QL, des ambient temperature t e [ C] if Q k = konst if Q k = / konst - graph

33 Example 33/51 family house design load 15 kw for design temperature -15 C heat pump (SE WPL18) heating system 50/40 C Q k =10.5 kw determine the balance point balance point heat output balance point power input balance point COP

34 Flow temperature 34/51 flow temperature [ C] C t w1 t w1, des t flow t w1 return t w2 w1, des t w1,min t t e i t t e, des e, des ambient temperature t e [ C]

35 Power input at balance point 35/51 for balance power point t v1 = -5 C, t k2 = 42 C P 35 = 3.3 kw P 50 = 4.5 kw interpolation P tw1 t w1 P P 50 P P tw1 P 35 P 50 P 35 tw balance power point P 42 = 3.9 kw

36 Example 36/51 COP tw1 COP 50 COP 35 COP tw COP 35 COP 50

37 Example 37/51 family house design load 15 kw for design temperature -15 C heat pump (SE WPL18) heating system 50/40 C Q k =10.5 kw determine the balance point balance point heat output balance point power input balance point COP balance point COP = balance power point P 42 = 3.9 kw

38 Heat pump sizing coverage of demand 38/51 outdoor temperature t e [ C] % days 100% 75% 50% 25% 0%

39 supplied energy by HP / heating demand Heat pump sizing coverage of demand 39/51 1,0 0,9 a r 0,8 0,7 0,6 0,5 residential sector based on heating demand 0,4 0,3 0,2 0,1 0,0 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 HP heating output / design a heating load

40 Heat pump sizing (ground source) 40/51 dimensioning heat output (independent on ambient conditions) 50 % heat loss - coverage 85 % heat demand 60 % heat loss coverage 93 % heat demand 70 % heat loss - coverage 97 % heat demand water-water

41 Heat pump sizing (air source) 41/51 dimensioning heat output (dependent on ambient conditions) 50 % heat loss - coverage 75 % heat demand 60 % heat loss coverage 85 % heat demand 70 % heat loss - coverage 92 % heat demand air-water

42 Heating capacity control 42/51 usual heat pumps start-stop regime cycling = reduction of durability compressor elimination cycling undersizing heat storage sizing of store for minimum operation time of heat pump heat pump with heating capacity control compressor speed control possibility for monovalent operation

43 Heating capacity control 43/51 30 Without capacity control heat output Q k [kw], heat load Q l [kw] backup output temperature 35 C output temperature 50 C heat load part load cycling ambient temperature t e [ C] backup 100% With capacity control part load cycling 30%

44 Heat storage for heat pump 44/51 oversized storage for most of operation time balancing heat output and heat load reduction of frequency compressor on/off (1 x 10 min) longer durability of compressor heat source for outdoor units (air-water) antifreeze protection

45 Heat storage for heat pump 45/51 hydraulic decoupling of heat pump from load circuit hydraulic shunt heating systems can t influence HP circuit providing required (higher) flowrates at condenser heating system heat pump storage tank

46 Sizing of storage tank 46/51 balance to reduce on/off frequency minimum operation time period Dt increase of temperature Dt in store during operation of heat pump heat stored during operation of heat pump Q stored Q HP Dt V c Dt

47 Sizing of storage tank 47/51 specific volume V Q HP 1000 Dt c Dt Dt [s] minimum operation time: 15 min Dt [K] increase of store temperature: 3-5 K usually 15 to 30 l/kw thermal capacity (momentum) of heating system results in lower volume requirement

48 Example 48/51 calculate heat storage volume for balance point heat output 10.5 kw minimum operation time period Dt = 15 min increase of temperature Dt in store 3 K V Q HP 1000 Dt c Dt V 3 [m ] Q HP [kw ] V = 754 l

49 Integration of store 49/51 electronically controlled pump heat pump control temperature sensor pump bypass valve heating system storage tank

50 Hydraulics 50/51 with two stores heating water store, hot water store bivalent (back-up) heater inside heat pump HW EL.HEATER SH heating system HW CW

51 Hydraulics 51/51 with central store hot water heated in heat exchanger immersed in heating water store volume bivalent (back-up) heater: immersed in store HW EL.HEATER heating system HEAT PUMP CW

52 Guides for design 52/51 low temperature heating < 45 C floor heating, wall heating radiators with larger surface pool water heating hot water low temperature 45 C air-water: advantage in summer, high ambient temperatures brine-water: reduction of borehole regeneration (!)