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Low Temperature District Heating & Renewable Energy

More detail can be reached in my PhD Thesis. https://www.researchgate.net/profile/Hakan_Tol

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Low Temperature District Heating & Renewable Energy

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  1. District Heating in Areas with Low Energy HousesDetailed Analysis of District Heating Systems based on Low Temperature Operation and Use of Renewable EnergyDefense for the Degree of Doctor of PhilosophyHakan İbrahim TolFebruary 2015Kgs. Lyngby, Denmark

  2. CONTENT OF PRESENTATION • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies Allocated time: 45 minutes

  3. FOLLOWING THE CONTENT • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

  4. PREVIOUS REDUCTIONS OF TEMPERATURE • In the early stages of the use of district heating systems, the distribution of heat took place through the use of steam as the heat-carrying medium. • the newly built systems that evolved were based on super-heatedwater, its temperature at about 120 °C, and afterwards on hot water, at a temperature of about 90 °C. • Further reduction in the supply temperature was achieved by pertaining trials of decreasing 5 °C of the supply temperature each week from 85 °C to 70 °C in an operating Danish district heating system. • In more recent developments low-energy district heating systems operating at very low temperatures, 55 °C in the case of supply and 25 °C in the case of return, were found to satisfy the heating demands of low-energy houses when control of the substations was adequate.

  5. SUCCESSFUL EXAMPLES

  6. Lystrup, Denmark • Heat Supply to: • 40 terracedlow-energy houses, each 87-109 m2 • A communal building • Substations (Differing in domestic hot water production) • 3 kW with 120 L storage tank • 32.3 kW with instantenous production

  7. SSE Greenwatt Way Development, UK • Heat Sources: • Air Source Heat Pump, • Ground Source Heat Pumps • Biomass Boiler • Supply of 55 °C to: • 10 dwellings

  8. Kırşehir District Heating, Türkiye • 1,800 dwellings in high-rise multi-family buildings since 1994with outdoor design temperature of -12 °C

  9. ADVANTAGES OF LOW-TEMPERATURE OPERATION

  10. REDUCTION IN HEAT LOSS Heat Loss 80 ͦ C 50 ͦ C 40 ͦ C 20 ͦ C Leakage

  11. INCREASE OF EFFICIENCY OF EXISTING SOURCES &LOW-GRADE HEAT SOURCES Industrial Waste Heat Waste Incineration Plant Biomass CHP Solar Heat Waste Heat of Chillers Geothermal Sources

  12. IMPROVED INDOOR AIR QUALITY Lower Vertical Temperature Differences Possible Scalding or Skin Burns Dust Burning Lower Air Speeds

  13. FOLLOWING THE CONTENT • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

  14. The Major Aim • An infrastructural transformation process for Danish Municipalities involving; • (i) developing a method for designing low-energy district heating systems considered for new settlements, • (ii) developing a method for designing low-energy district heating systems for already existing settlements involving existing buildings in use of existing old in-house heating systems and • (iii) developing a decision support tool in planning for the use of renewable energy sources as heat sources for low-energy district heating systems. Regarding the heat supply, strong emphasis is placed on matters of sustainability, security of supply and reliability. Hypotheses • A detailed analysis of energy performance and of overall costs of low-energy district heating systems can be used as a rational basis for planning the use of low-energy district heating in areas in particular in which low energy houses are built.

  15. FOLLOWING THE CONTENT • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

  16. Purpose and Scope • The first research question is that of what method or methods can best be used to determine the most energy-efficient and sustainable optimal dimensioning of a low-energy district-heating piping network, together with the substation types and the network layouts that can most fruitfully be employed. • The second research question concerns the technical possibilities of integrating the use of low-energy district heating systems in already existing settlements with the existing in-house heating systems. • The third research question concerns that of how a decision support tool can be developed for determining the optimal capacities of renewable-energy-based energy conversion systems for supplying heat to low-energy district heating systems and the technical specifications such a tool should meet. RQ1 RQ2 RQ3

  17. CONNECTION OF RESEARCH QUESTIONS

  18. FOLLOWING THE CONTENT • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

  19. Article-Based Dissertation RQ1 RQ1 RQ2 RQ1 RQ3 RQ3

  20. Conference Dissertations ISI-1 ISI-2 ISI-3 ISIs N-ISI ISI-3 BCs

  21. FOLLOWING THE CONTENT • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

  22. DETERMINATION OF HEAT LOAD ON PIPES

  23. RQ1 ISI-1 SITE DESCRIPTION • Number of Houses • 165 • Low Energy House (Class I) • 3 kW Space Heating • 3 kW Domestic Hot Water (120 l buffer tank) • 32 kW Domestic Hot Water (without tank) SEMI-DETACHED SINGLE FAMILY HOUSES NEW LOW ENERGY DH SYSTEM • StaticPressure • 10 bar • Max AllowablePressure Drop • 8 bar • Total Length of Network • ~1 km • Pipe Type (Class I) • AluFlex TwinPipe • DN14 – DN32 • Steel TwinPipe • DN32 – DN80

  24. DH NETWORK = NODE & PIPE SEGMENTS RQ1 ISI-1 Pipe Segment

  25. DETERMINATION of HEAT LOAD RQ1 ISI-1 SF for 6 • Simultaneity Factor in each Segment • with Peak Heat Demand Values • Considering Each Route in the Network • Max Pressure Gradient Method • Optimization SF for 165

  26. DETERMINATION OF DIMENSIONING METHOD

  27. PRESSURE GRADIENT METHODCRITICAL ROUTE (THE RULE-OF-THUMB) RQ1 ISI-1 1,617 1,617 1,617 1,617 1,617 1,617 1,617 1,617 Pressure Gradient in Pa/m

  28. PRESSURE GRADIENT METHODMULTI ROUTE RQ1 ISI-1 1,617 2,491 3,388 4,643 2,141 2,563 3,520 4,651 Pressure Gradient in Pa/m

  29. OPTIMIZATION METHOD RQ1 ISI-1 Nonlinear Constraint Function Optimization 8 bar 8 bar 8 bar Decision Variables: Pipe Diameters 8 bar Objective Function: Min Heat Loss from DH Network 8 bar Constraint Functions: Max Allowable Pressure Loss in each Route (8 bar) 8 bar 8 bar 8 bar

  30. COMPARISON (DIMENSIONING METHODS) RQ1 ISI-1 -%3 -%14 Reduction in Heat Loss

  31. SUBSTATION TYPE & BOOSTER PUMPS

  32. BOOSTER PUMP RQ1 ISI-1 ISI-2 Booster Pumps Main Pump Station

  33. COMPARISON (SUBSTATION TYPES&BOOSTER PUMP) RQ1 ISI-1 ISI-2 Same optimization method applied to all. Without Booster Pump -%3 -%7 Reduction in Heat Loss

  34. SUMMER CONDITION

  35. SUMMER COND. IN BRANCHED NETWORK RQ1 ISI-1 ISI-2 By-Pass in End-Users

  36. SUMMER COND. IN LOOPED NETWORK RQ1 ISI-1 ISI-2

  37. DYNAMIC SIMULATION RQ1 ISI-1 ISI-2 Scenarioswith Various Level of Heat Consumption For 25, 50, 75% existance of consumers at the DH network

  38. RQ1 ISI-1 ISI-2 UNSATISFIED NODES (For 25% Existance Ratio) Heat loss is higher in looped network than branched network with by-pass valves.

  39. MAXIMUM STATIC DESIGN PRESSURE

  40. RQ1 N-ISI EFFECT OF STATIC PRESSURE

  41. RQ1 N-ISI COMPARISON (MAXIMUM STATIC PRESSURE) Maximum Static Pressure Limit (>10 bara) AluFlex cannot be used!

  42. RQ1 N-ISI EFFECT OF STATIC PRESSURE ON OVERALL COST

  43. Following the Presentation Content • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

  44. RQ2 ISI-3 REPLACING OLD HEATING SYSTEM Natural Gas Heating System or High Temperature District Heating Low-Energy District Heating System

  45. RQ2 ISI-3 SITE DESCRIPTION • Number of Houses • 780 • Heat Demand [kW] DETACHED SINGLE FAMILY HOUSES • PIPE TYPE (CLASS I) • AluFlex Twin Pipe : DN14 – DN32 • Steel Twin Pipe : DN32 – DN80 • Single Pipe : DN100 – DN200 • LOW-ENERGY DISTRICT HEATING NETWORK • Max Static Pressure : 10 bar • Max Pressure Drop : 8 bar • Total Length of Network : 9.3 km

  46. RQ2 ISI-3 SUBSTATION & IN-HOUSE INSTALLATION Substation Existing Radiator System (CS) Space Heating Nominal Capacity: 9 kW Storage Tank (120 liter) Heat Supply Domestic Hot Water After Renovation (FS) Current Heat Demand: 5.1 kW • 3 kW Space Heating • 3 kW Domestic Hot Water

  47. RQ2 ISI-3 OPERATIONAL PHILOSOPHY: BOOSTING SUPPLY TEMPERATURE Current Situation (Buildings without renovation) Future Situation (All buildings renovated)

  48. RQ2 ISI-3 EFFECT OF BOOST OF SUPPLY TEMPERATURE

  49. RQ2 ISI-3 COMPARISON (BOOST OF SUPPLY TEMPERATURE) Without Boosting With Boosting 40% of Pipe Investment Cost can be saved with boosting supply temperature in peak periods

  50. Following the Presentation Content • Literature Review • Aim and Hypothesis • Purpose and Scope • Disposition of the PhD Thesis • Research Questions Studied • Design of DH network for new settlements • Design of DH network for existing settlements • Non-fossil fuel heat sources for low-energy DH • Conclusions • Further Studies

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