HVAC SYSTEMS - HFT Stuttgart

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Page - 10 - CHAPTER 01 analysed in different levels of detail. Dynamic system simulations are used for the analyses of the complex systems in the simulation environment INSEL. The main tasks and objectives of the presented work can be summarised as follows: - Dimensioning strategies for solar driven absorption cooling systems The aim of chapter 3 of this work is to analyse and highlight the influencing factors on the design of solar driven absorption cooling systems. The factors addressed are different cooling load characteristics caused by high or low internal loads, different building orientations and locations. Furthermore, the influence of different system configurations (high / low temperature cold distribution, dry or wet heat rejection) and the influence of different control strategies (constant or variable generator inlet temperatures) on the system design are addressed. A detailed cooling cost analysis highlights applications and configurations which offer the potential for a cost effective implementation of the innovative technology in the near future. - Model based control strategy optimisation of solar driven absorption cooling systems Chapter 4 of this work aims to give a clear set of recommendations on the control strategies and system configurations required for a highly energy efficient operation of solar driven absorption cooling systems. Therefore, detailed analyses are performed to highlight the influence of different control strategies and system configurations on the overall primary energy efficiency. These controls strategies and system configurations are analysed in the simulation environment for a solar cooling system installed in Germany. The main influencing factors addressed are the cooling tower type (dry or wet), its temperature setpoint and the implementation of a fan speed control. Furthermore, the control of the generator inlet temperature (constant / variable) and the implementation of a mass flow control of the cold distribution pump are analysed.
Page - 11 - CHAPTER 01 For purely solar driven absorption chillers additionally strategies for an early systems startup and a high solar cooling fraction on the cooling energy demand of the building are developed. Here different hot water storage charge and discharge strategies with storage bypass and / or storage segmentation are analysed and compared. - Model based development of primary energy optimised control strategies for open desiccant evaporative cooling systems (DEC) The main aim of chapter 5 is to develop a control strategy which efficiently avoids the typical control problems found for installed desiccant evaporative cooling systems in order to improve their primary energy efficiency. An electricity optimised standard sequence controller is used with control support from a primary energy optimisation tool. The aim of this newly developed primary energy optimisation tool is a continuously evaluation of the optimum operation mode for the actual weather and room air conditions. This tool is supposed to be operated as ‘online tool’ which allows or blocks possible operation modes in the sequence controller. Furthermore, it includes a control support for the supply air humidifier to ensure a stable and efficient operation.
Page 1: MODEL BASED CONTROL OPTIMISATION OF
Page 4 and 5: IV ABSTRACT - For optimised control
Page 6 and 7: ACKNOWLEDGEMENTS VI ACKNOWLEDGEMENT
Page 8 and 9: TABLE OF CONTENT VIII TABLE OF CONT
Page 10 and 11: X TABLE OF CONTENT 4.5 ANALYSIS AND
Page 12 and 13: XII TABLE OF CONTENT 6.2 MODEL BASE
Page 14 and 15: NOMENCLATURE Latin letters A [m²]
Page 16 and 17: Greek Letters α [W/m² K] heat tra
Page 18 and 19: wb wet bulb Abbreviations ACM Absor
Page 20 and 21: Page - 2 - CHAPTER 01 a thermal coo
Page 22 and 23: Page - 4 - CHAPTER 01 explains the
Page 24 and 25: Page - 6 - CHAPTER 01 The concept o
Page 26 and 27: Page - 8 - CHAPTER 01 Mean calculat
Page 30 and 31: 2. MODEL DEVELOPMENT FOR SOLAR COOL
Page 32 and 33: Page - 14 - CHAPTER 02 In the prese
Page 34 and 35: Page - 16 - CHAPTER 02 Within chapt
Page 36 and 37: Page - 18 - CHAPTER 02 b) Simple on
Page 38 and 39: Page - 20 - CHAPTER 02 is off. For
Page 40 and 41: Page - 22 - CHAPTER 02 Since only s
Page 42 and 43: Page - 24 - CHAPTER 02 negative eff
Page 44 and 45: 2.2.1.4 Tubing Page - 26 - CHAPTER
Page 46 and 47: tube fl fl tube tubel Page - 28 - C
Page 48 and 49: Temperature / °C 90 80 70 60 50 40
Page 50 and 51: TH 8 9 Qc & C G E Qe & Fig. 2-6: Sy
Page 52 and 53: Page - 34 - CHAPTER 02 The enthalpy
Page 54 and 55: Page - 36 - CHAPTER 02 With: Heat l
Page 56 and 57: Page - 38 - CHAPTER 02 The so calle
Page 58 and 59: Page - 40 - CHAPTER 02 To further i
Page 60 and 61: Page - 42 - CHAPTER 02 2.2.2.2 Para
Page 62 and 63: e e Page - 44 - CHAPTER 02 The char
Page 64 and 65: Page - 46 - CHAPTER 02 and chapter
Page 66 and 67: Model for the dynamic parts of the
Page 68 and 69: - Absorber/Condenser Q g _ ac & & Q
Page 70 and 71: Page - 52 - CHAPTER 02 cross sectio
Page 72 and 73: Page - 54 - CHAPTER 02 conditions l
Page 74 and 75: With: tw,in tw,out twb Water inlet
Page 76 and 77: l min m& = m& a w = c ( h − h ) a
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Page - 60 - CHAPTER 02 If the cooli
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Page - 62 - CHAPTER 02 As already d
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Page - 64 - CHAPTER 02 only very fe
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Page - 66 - CHAPTER 02 rejection sy
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Page - 68 - CHAPTER 02 and the UA v
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Page - 70 - CHAPTER 02 different ve
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Page - 72 - CHAPTER 02 −4 −2 2
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Page - 74 - CHAPTER 02 Fig. 2-25: M
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Page - 76 - CHAPTER 02 difference i
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Page - 78 - CHAPTER 02 In this quit
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- Absorbed solar energy Gt , a t a
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CHAPTER 02 Page - 82 - a b a r a a
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Page - 84 - CHAPTER 02 The area rel
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Page - 86 - CHAPTER 03 conditions.
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Page - 88 - CHAPTER 03 was calculat
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Page - 90 - CHAPTER 03 The same bui
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Page - 92 - CHAPTER 03 The specific
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Cooling / Heating power / kW 50 40
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Page - 96 - CHAPTER 03 As visible f
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3.4.2 SOLAR THERMAL SYSTEM MODELS P
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Page - 100 - CHAPTER 03 generator i
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m² kW-1 m² kW-1 Page - 102 - CHAP
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Page - 104 - CHAPTER 03 Fig. 3-16:
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Page - 106 - CHAPTER 03 m 2 kW -1 s
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a f N d ( 1 + d ) ( 1 + d ) − 1 P
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Page - 112 - CHAPTER 03 costs Csola
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Page - 116 - CHAPTER 03 The total a
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Page - 118 - CHAPTER 04 4. Model Ba
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Page - 120 - CHAPTER 04 Germany. De
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Page - 122 - CHAPTER 04 Fig. 4-2: A
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Page - 124 - CHAPTER 04 4.3.2 SYSTE
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Page - 126 - CHAPTER 04 temperature
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Page - 128 - CHAPTER 04 System part
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Page - 130 - CHAPTER 04 performance
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Fig. 4-5: Measured and simulated pe
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Page - 134 - CHAPTER 04 An addition
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Fig. 4-6: Annual electricity consum
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Page - 138 - CHAPTER 04 The values
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Page - 140 - CHAPTER 04 EAW WERACAL
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4.4.6 CONCLUSIONS Page - 142 - CHAP
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Page - 144 - CHAPTER 04 4.5 Analysi
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4.5.2 SIMULATION MODEL AND VALIDATI
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Page - 148 - CHAPTER 04 the start u
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Table 4-4: Analysed storage charge
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4.5.5 RESULTS AND DISCUSSION 4.5.5.
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Page - 154 - CHAPTER 04 Although co
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Page - 156 - CHAPTER 04 At 09:10am
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Fig. 4-16: Detailed simulation resu
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Fig. 4-17: Detailed simulation resu
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Page - 162 - CHAPTER 04 The thermal
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Page - 164 - CHAPTER 04 Table 4-7:
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4.5.6 CONCLUSIONS Page - 166 - CHAP
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Page - 168 - CHAPTER 04 considered
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Page - 170 - CHAPTER 05 5. MODEL BA
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Page - 172 - CHAPTER 05 optimised s
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Page - 174 - CHAPTER 05 The electri
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5.3.2 DESCRIPTION OF THE CONTROL SY
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Page - 180 - CHAPTER 05 The time se
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5.3.4 ROOM UTILISATION Page - 184 -
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P 3 3 2 2 2 1 1 ⎟ 1 1 ⎟ ⎛ n
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Page - 188 - CHAPTER 05 dehumidific
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Page - 190 - CHAPTER 05 The high ab
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5.4.3 RETURN AIR HUMIDIFIER Page -
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5.4.4 SUPPLY AIR HUMIDIFIER Page -
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Relative humidity / Error / % 120 1
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Fig. 5-22: Detailed view into the r
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Page - 202 - CHAPTER 05 simplificat
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Page - 204 - CHAPTER 05 The relativ
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Cooling power / kW . 14 12 10 8 6 4
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Page - 210 - CHAPTER 05 only slight
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t ⎛ ⎜ 1 u ( t ) = K p ⎜ e ( t
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5.6.2 PE-OPTIMISER (ONLINE TOOL) Pa
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Tr9, xr9 Fig. 5-30: System scheme w
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h h x s 3, max s 3, max max, s 3 =
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Page - 220 - CHAPTER 05 the supply
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Page - 222 - CHAPTER 05 humidificat
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Page - 224 - CHAPTER 05 case 4 the
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Page - 226 - CHAPTER 05 Case 4: Ele
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Page - 228 - CHAPTER 05 shows a sta
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Fig. 5-40: Distribution of the DEC
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Page - 232 - CHAPTER 05 the operati
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5.8.2 DETAILED PERFORMANCE COMPARIS
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Page - 236 - CHAPTER 05 The perform
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Page - 238 - CHAPTER 05 The advance
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Page - 240 - CHAPTER 05 regarded da
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Page - 242 - CHAPTER 05 After the b
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Page - 244 - CHAPTER 05 the DEC sys
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5.9 CONCLUSIONS Page - 248 - CHAPTE
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Page - 250 - CHAPTER 05 to compete
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6.1 SOLAR DRIVEN CLOSED ABSORPTION
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Page - 254 - CHAPTER 06 6.1.2 MODEL
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Page - 256 - CHAPTER 06 more coolin
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considered and compared: Page - 258
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7. CONCLUSIONS AND OUTLOOK 7.1 SOLA
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Page - 262 - CHAPTER 07 Apart from
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Page - 264 - CHAPTER 07 7.2 PRIMARY
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Page - 266 - CHAPTER 07 therefore b
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REFERENCES Page - 268 - REFERENCES
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Page - 270 - REFERENCES Park, C., D
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OWN PUBLICATIONS Page - 272 - OWN P
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MODEL DEVELOPMENT 1. ABSORPTION CHI
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With these simplifications we get:
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− t + t E E 9 ⋅ K U Z + t U Z +
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4 4 ⎛ i ⎞ t LiBr ( X , p s ) =
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APPENDIX A: MODEL DEVELOPMENT Page
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C) Absorber/Condenser Q g _ ac & &
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Page - 292 - APPENDIX A: MODEL DEVE
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Page - 294 - APPENDIX A: MODEL DEVE
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Electric power [kW] 0,4 0,35 0,3 0,
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Water consumption [kg/h] 350 300 25
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Technical Data of the Axima Wet Coo
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5. SOLAR COLLECTORS APPENDIX B: SOL
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APPENDIX B: SOLAR COOLING SYSTEM 7.
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3. Cold Storage Tank APPENDIX B: SO
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Case 2: Full storage with bypass De
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APPENDIX C: OPTIMISED CONTROL SEQUE
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APPENDIX D: DETAILED SIMULATION RES
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Module Number 20 2P100 21 2P100 22
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HVAC SYSTEMS - HFT Stuttgart

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