Feasible Working Domains Decision Support for Heat Pump Projects

Transcription

1 Downloaded from orbit.dtu.dk on: Nov 8, 17 Feasible Working Domains Decision Support for Heat Pump Projects Ommen, Torben Schmidt Publication date: 15 Document Version Peer reviewed version Link back to DTU Orbit Citation (APA): Ommen, T. S. (15). Feasible Working Domains Decision Support for Heat Pump Projects [Sound/Visual production (digital)]. 4th International Symposium on Advances in Refrigeration and Heat Pump Technology, Odense, Denmark, 19/11/15 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

2 Feasible Working Domains Decision Support for Heat Pump Projects 4th International Symposium on Advances in Refrigeration and Heat Pump Technology November 19 th 15 Torben Ommen Section of Thermal Energy, Technical University of Denmark

3 Introduction Motivation Potential for energy and economic optimisation in industrial plants and district heating systems by using large scale heat pumps. Complex systems: economic optimum depends on both heat pump performance, investment, expected operation hours, taxation and fuel cost. Pinch- or plant optimisation specialists are not necessarily experts on best available heat pump technology, and may thus be assisted by decision support tools. 2 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

4 Introduction Motivation Potential for energy and economic optimisation in industrial plants and district heating systems by using large scale heat pumps. Complex systems: economic optimum depends on both heat pump performance, investment, expected operation hours, taxation and fuel cost. Pinch- or plant optimisation specialists are not necessarily experts on best available heat pump technology, and may thus be assisted by decision support tools. Working domains Introduced in Comparison of the working domains of some compression heat pumps and a compression-absorption heat pump by Brunin et al. (1997) Economic feasibility integrated by including two physical constraints Technical constraints are similar to operating envelope for individual components Technical and economical working domains for single stage industrial heat pumps. R134a, R29, R6a, R717-LP, R717-HP and R744 in Ommen et al. (15a) Ammonia-water hybrid absorption compression HP in Jensen et al. (15) R6a and R717-HP in series in Ommen et al. (15b) 2 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

5 Introduction Working domains in literature, < () Max. pressure Max. pressure () Working Domain Working Domain <, (), () (a) Example of working domain with VHC and COP to represent economic feasibility (Brunin et al., 1997) (b) Example of working domain with economic and technical constraints (Ommen et al., 15a). 3 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

6 Method Outline for Presentation Introduction Motivation Working domains in literature Method Vapour compression heat pump Economic assumptions Heat exchanger design and calculation Influence of key economic assumptions on NPV Examples of working domains Single stage vapour compression HP Ammonia-Water Hybrid Compression-Absorption HP Vapour compression HPs in series Vapour compression HPs in series COP and NPV Comparison with working domain for single stage VCHP Further steps A second economic case Two stage VCHP configurations Discussion 4 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

7 Method Vapour compression heat pump 1 8 Refrigerant Sink media Source media T cond 3 Expansion valve 4 Condenser Evaporator Compressor 2 1 Gross Temp. lift sink T lift T sink T source T ( o C) 6 4 T pinch T pinch T pinch Temperature variation of sink stream Temperature variation of source stream T evap (a) Principle sketch of VCHP T source.5 1 Relative heat transfer (-) (b) Temperature - heat load diagram of VCHP 5 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

8 Method Vapour compression heat pump in finite reservoirs Typically used operational parameters for heat pump performance: Type of data Value Unit Designation Efficiency.8 / Compressor isentropic efficiency.8 / Compressor volumetric efficiency.95 / Electric motor efficiency Temperature 5 K Evaporator superheat 5 K Minimum pinch point in heat exchangers 6 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

9 Method Economic assumptions Heat pump load: 1 (kw) Operating time 35 (h/year) Lifetime 15 (years) Natural gas burner efficiency.9 (-) Interest rate of 7 (%) Inflation rate of 2 (%) NPV and PBT based on gas boiler replacement Component investment cost based on Danish prices Danish electricity and gas prices were used Natural gas burner investment and O&M not considered Correlations for component cost of the type: PEC Y = PEC W ( XY X W ) α: Component type PEC W (e) X W α( ) Source Compressor R6a (m 3 h 1 ).73 trade business 1 2 R717-HP NDA NDA NDA manufacturer 4 Electrical motor R6a incl. in compressor 1 2 R717-HP (kw).65 trade business 1 Receiver R6a (m 3 ).63 trade business 1 R717-HP (m 3 ).66 trade business 1 Plate heat exchanger R6a (m 2 ).8 trade business R717-HP NDA NDA NDA manufacturer 5 1 (H. Jessen Jörgensen A/S (13)) 2 (FK Teknik A/S (13)) 3 (Ahlsell Danmark ApS (13)) 4 (Johnson Controls, Inc. (13)) 5 (SWEP International AB (13)) 7 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

10 Method Heat exchanger design and calculation All HEX are plate type with chevron corrugation Commercial plate sizes were applied Mass and liquid/vapour maldistribution was neglected Counter flow arrangement Heat transfer and pressure drop correlations from literature was applied Component Media Zone Heat transfer Pressure drop Condenser H 2O Martin (1996) Martin (1996) Condenser Rxxx vapour only: Martin (1996) Martin (1996) two-phase: Yan et al. (1999) Yan et al. (1999) transcritical: Martin (1996) Martin (1996) liquid only: Martin (1996) Martin (1996) Evaporator H 2O Martin (1996) Martin (1996) Evaporator Rxxx two-phase: Yan and Lin (1999) Yan and Lin (1999) vapour only: Martin (1996) Martin (1996) 8 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

11 Method Influence of key economic assumptions on NPV Operating hours (h) NPV= EUR PBP=4 years PBP=8 years Q (kw) (a) NPV of HP system with variations in size and yearly operation hours NPV (1 6 EUR) Difference in cgas (%) celec < cgas NPV= EUR Difference in c elec (%) (b) NPV of HP system with variations in fuel cost NPV (1 6 EUR) Figure: R717-HP heat pump operating at T sink,out = 6C, T lift = C, T sink = K, T source=1 K 9 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

12 Examples of working domains Outline for Presentation Introduction Motivation Working domains in literature Method Vapour compression heat pump Economic assumptions Heat exchanger design and calculation Influence of key economic assumptions on NPV Examples of working domains Single stage vapour compression HP Ammonia-Water Hybrid Compression-Absorption HP Vapour compression HPs in series Vapour compression HPs in series COP and NPV Comparison with working domain for single stage VCHP Further steps A second economic case Two stage VCHP configurations Discussion 1 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

13 Examples of working domains Examples of working domains for single stage vapour compression HP 7 6 Tsource,out< C NPV < PBP > 8 Tsource,out< C NPV < PBP > 8 5 TH > TH,max TH > TH,max Four different sink and source temperature glides investigated T sink / T source 1K/1K K/1K K/K 4K/1K Tlift (K) Tlift (K) ph > ph,max PBP > 4 Tsink,in < Tsource,in (c) LP R717 Tsource,out< C NPV < ph > ph,max Tsink,in < Tsource,in Tsource,out< C NPV < ph > ph,max ph > ph,max PBP > 4 (d) HP R717 PBP > 8 PBP > 8 1 Tsink,out Tlift : PBP > 4 (e) R6a Tsink,out Tlift : TH < TH,max Tsink,out ( C) Tsink,out Tlift : PBP > 4 Tsink,out Tlift : TH < TH,max (f) R134a Tsink,out ( C) 11 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

14 Examples of working domains Examples of working domains for single stage vapour compression HP Four different sink and source temperature glides investigated T sink / T source 1K/1K K/1K K/K 4K/1K Tlift (K) Tlift (K) Tsource,out< C Tsink,in < Tsource,in Tsource,out< C (a) R134a R6a R29 R744 R717 LP R717 HP Tsink = 1K Tsource = 1K R134a R6a R29 R744 R717 LP R717 HP Tsource,out< C Tsink,in < Tsource,in Tsource,out< C Low pressure R717 High pressure R717 R6a Tsink = 1K (b) Tsource = 1K 1 R6a Tsink,in < Tsource,in Tsink = K High pressure R717 Tsink = K (c) (d) Tsource = K Low pressure R717 Tsource = K T sink,out ( C) T sink,out ( C) 12 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

15 Examples of working domains Ammonia-Water Hybrid Compression-Absorption HP Sink Sink T 3 T 4 Mixing (adiabatic absorption) Reciever Throttling valve 4 Source Absorber Internal HEX 5 6 Desorber Mixer Pump 3 2 Source 1 7 j k Rich xr Lean xl Vapour xv Water Stream Component Compressor Liquid-vapour separator Temperature ( C) T sink,out T 5 T sink,in T source,in T 1 T source,out T 7 Absorption curve Heat source Heat sink Desorption curve Q Desorber Q Absorber Ẇ T sink T lift T source Heat Load (kw) (a) Principle sketch of the HACHP (b) Temperature - heat load diagram of the HACHP 13 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

16 Examples of working domains Examples of working domains for Ammonia-Water Hybrid Compression-Absorption HP Four different sink and source temperature glides investigated T sink / T source 1K/1K K/1K K/K 4K/1K Tlift (K) Tlift (K) Tsource,out< C -3.%< rpv <8.% -.5%< rpv <16% Tsource,out< C -2.%< rpv <9% 1.%< rpv <19% -.5%< rpv <14%.5%< rpv <17% VS. LP HACHP LP R717 HP R717 23%< rpv <45% VS. HP HACHP HP R717 R6a Tsink = 1K (a) Tsource = 1K 37%< rpv <78% Tsource,out< C VS. LP HACHP LP R717 HP R717 Tsource,out< C VS. HP HACHP HP R717 R6a -.5%< rpv <6.% 3.%< rpv <16% 4.%< rpv <13% 35% < rpv <52% Tsink = K (b) Tsource = K 9.%< rpv <18% 43%< rpv <56% -1.%< rpv <6.% -1.%< rpv <8.% -5.%< rpv <7.% LP HACHP HP HACHP LP HACHP HP HACHP VS. VS. VS. VS. LP R717 HP R717 1 LP R717 HP R717 Tsink = K HP R717 R6a Tsink = 4K HP R717 R6a (c) (d) Tsource = 1K R744 Tsource = 1K T sink,out ( C) T sink,out ( C) 14 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

17 Examples of working domains Differences in investment cost for VCHP and HACHP Tlift (K) Tsource,out< C Tsink,in < Tsource,in ph > pcrit Investement (1 3 EUR) Tlift (K) Tsink,out< C Tsink,in < Tsource,in Investement (1 3 EUR) T sink,out ( C) T sink,out ( C) 3 (a) VCHP (R717-HP) (b) HACHP (R717-HP) Figure: Investment cost for VCHP and HACHP at T sink =1 K / T source=1 K. 15 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

18 Vapour compression HPs in series Outline for Presentation Introduction Motivation Working domains in literature Method Vapour compression heat pump Economic assumptions Heat exchanger design and calculation Influence of key economic assumptions on NPV Examples of working domains Single stage vapour compression HP Ammonia-Water Hybrid Compression-Absorption HP Vapour compression HPs in series Vapour compression HPs in series COP and NPV Comparison with working domain for single stage VCHP Further steps A second economic case Two stage VCHP configurations Discussion T ( o C) Refrigerant Sink media Source media Q cond,2 Q evap,2 Ẇ 2 Counter Current Configuration Q cond,1 Q evap,1 Ẇ Heat load (MW) Temperature variation of sink stream Temperature variation of source stream 16 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

19 Vapour compression HPs in series Vapour compression HPs in series T ( o C) Refrigerant Sink media Source media Q cond,2 Q evap,2 Ẇ 2 Counter Current Configuration Q cond,1 Q evap,1 Ẇ Heat load (MW) Temperature variation of sink stream Temperature variation of source stream T ( o C) T ( o C) T ( o C) Co Current Configuration 1 Heat load (MW) Parallel Evaporator 1 Heat load (MW) Parallel Condenser 1 Heat load (MW) Temperature variation of sink stream Temperature variation of source stream Temperature variation of sink stream Temperature variation of source stream Temperature variation of sink stream Temperature variation of source stream 17 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

20 Vapour compression HPs in series COP and NPV of VCHPs in series Deviation from reference system (%) COP NPV Counter current Co current Parallel Evap. Parallel Cond. No Series 2 3 Number of HP in series Deviation from reference system (%) COP NPV Counter current Co current Parallel Evap. Parallel Cond. No Series 2 3 Number of HP in series (a) T sink / T source =K/K (b) T sink / T source =4K/1K Figure: Changes to COP and NPV for four serial connected HP schemes with even heat load for serial connected units. COP and NPV are calculated for R717-HP units in series. 18 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

21 Vapour compression HPs in series Load sharing for two vapour compression HPs in series 5 5 x Tlift (K) COP ( ) Tlift (K) (bar) 18 ( o C) 35 (bar) 34 (bar) NPV (EUR) Heat load distribution for HP 1 (-) Heat load distribution for HP 1 (-).5 (a) COP (b) NPV Figure: COP and NPV variations with variation of the heat load fraction and temperature lift. Results are calculated for T sink = 7 (C) and T sink / T source =K/K. 19 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

22 Vapour compression HPs in series Comparison with working domain for single stage VCHP Tsource,out< C Tsource,out< C Two different serial connected VCHP investigated Tlift (K) Tsink,in < Tsource,in Tsink = K (a) Tsource = K Tsink,out ( C) Tlift (K) 4 Tsink,in < Tsource,in 3 R6a R744 R717 LP R717 HP 1 Series 1#1 Tsink = 4K Series 2#2 (b) Tsource = 1K Tsink,out ( C) 7 7 HP 1 HP 2 #1 R717-HP R717-HP #2 R6a R717-HP 6 5 Tsource,out< C 6 5 Tsource,out< C Tlift (K) 4 3 Tlift (K) 4 3 Tsink,in < Tsource,in 1 Series #2 Series #1 R6a High pressure R717 Low pressure R717 Tsink = K () Tsource = K Tsink,out ( C) 1 Series #2 Series #1 R744 R6a High pressure R717 Low pressure R717 Tsink = 4K () Tsource = 1K Tsink,out ( C) DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

23 Further steps Outline for Presentation Introduction Motivation Working domains in literature Method Vapour compression heat pump Economic assumptions Heat exchanger design and calculation Influence of key economic assumptions on NPV Examples of working domains Single stage vapour compression HP Ammonia-Water Hybrid Compression-Absorption HP Vapour compression HPs in series Vapour compression HPs in series COP and NPV Comparison with working domain for single stage VCHP Further steps A second economic case Two stage VCHP configurations Discussion DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

24 Further steps Two economic cases (industrial and DH) Deviation from reference system (%) COP Industrial NPV Industrial COP District Heating NPV District Heating No Series 2 3 Number of HP in series Deviation from reference system (%) COP Industrial NPV Industrial COP District Heating NPV District Heating No Series 2 3 Number of HP in series (a) T sink / T source = K / K (b) T sink / T source = 4 K / 1 K 22 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

25 Further steps Two stage HP configurations Individual models for each component - A high amount of configurations possible. - Generic solutions to optimal configurations are needed. - High amount of free variables, eg. oil integration only constrained to intervals. M (a) Heat exchangers not fixed connection to heat sink 23 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

26 Further steps HP configurations in series M M (a) Possibilities for creating various two stage HP cycle layouts 24 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

27 Discussion Outline for Presentation Introduction Motivation Working domains in literature Method Vapour compression heat pump Economic assumptions Heat exchanger design and calculation Influence of key economic assumptions on NPV Examples of working domains Single stage vapour compression HP Ammonia-Water Hybrid Compression-Absorption HP Vapour compression HPs in series Vapour compression HPs in series COP and NPV Comparison with working domain for single stage VCHP Further steps A second economic case Two stage VCHP configurations Discussion 25 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

28 Discussion Important findings from analysis The analysis of working domains shows, that sink temperatures of up to 1-14 C and temperature lifts 4-6 K may be obtained using VCHP and HACHP technologies. The NPV is favourable for the technologies utilising R717, but a technical constraint (the discharge temperature) limited the applicability in terms of temperature lift. Serial connection of VCHP increases the COP, but at decreased NPV. If more than one heat pump is needed due to capacity constriants, the increase in COP from serial connection of the considered units should be included. VCHP in series increases the working domain of current technical and economic constraints. Either due to reduction in resulting discharge temperature of compressor or mixed working fluids selection to obtain combination of certain characteristics. Further work and analysis is required to obtain generic tool, as a high amount of configurations are possible. Input are welcome for other HP configurations, changed temperature sets or economic cases. 26 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

29 Discussion Thank you for your attention If questions, new ideas or interest in new projects: Work funded by: Copenhagen Cleantech Cluster Dong Energy DTI DTU EUDP 27 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

30 Discussion References I Ahlsell Danmark ApS (13). Priskatalog 13. [accessed ]. Brunin, O., Feidt, M., and Hivet, B. (1997). Comparison of the working domains of some compression heat pumps and a compression-absorption heat pump. International Journal of Refrigeration, (5):38. FK Teknik A/S (13). Priskatalog 13. [accessed ]. H. Jessen Jörgensen A/S (13). Priskatalog 13. [accessed ]. Jensen, J., Ommen, T., Markussen, W., Reinholdt, L., and Elmegaard, B. (15). Technical and economic working domains of industrial heat pumps: Part 2 - ammonia-water hybrid absorption-compression heat pumps. International Journal of Refrigeration. Johnson Controls, Inc. (13). HPO R717 compressor cost - non-disclosure agreement. private communication. Martin, H. (1996). A theoretical approach to predict the performance of chevron-type plate heat exchangers. Chemical Engineering and Processing: Process Intensification, 35(4): Ommen, T., Jensen, J., Markussen, W., Reinholdt, L., and Elmegaard, B. (15a). Technical and economic working domains of industrial heat pumps: Part 1 - single stage vapour compression heat pumps. International Journal of Refrigeration. Ommen, T., Jensen, J., Markussen, W., and Elmegaard, B. (15b). Enhanced technical and economic working domains of industrial heat pumps operated in series. The International Institute of Refrigeration. SWEP International AB (13). SWEP - products and solutions - non-disclosure agreement. private communication. 28 DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology

31 Discussion References II Yan, Y. Y. and Lin, T. F. (1999). Evaporation heat transfer and pressure drop of refrigerant r-134a in a plate heat exchanger. Journal of Heat Transfer, 121(1): Yan, Y. Y., Lio, H. C., and Lin, T. F. (1999). Condensation heat transfer and pressure drop of refrigerant r-134a in a plate heat exchanger. International Journal of Heat and Mass Transfer, 42(6): DTU Mechanical Engineering 4th International Symposium on Advances in Refrigeration and Heat Pump Technology