analysis of thermodynamic processes with full
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Analysis of thermodynamic processes
with full consideration of real gas behaviour
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• What is TDT 2 ?
• How does it look like ?
• How does it work ?
• Examples
Contents
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Introduction
TDT is a Thermodynamic Design Tool, that supports the
design and calculation of energetic processes on a 1D
thermodynamic approach.
The software TDT can be run on Windows operating
systems (Windows XP, Windows Vista, Windows 7 and
Windows 8).
What is TDT ?
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TDT2 Features
TDT2 Features
1. High calculation accuracy: • real gas properties are considered on thermodynamic calculations
• change of state in each components is divided into 100 steps
2. Superior user interface: • ease of input: dialogs on graphic screen
• visualized output: graphic system overview, thermodynamic graphs,
digital data in tables
3. Applicable various kinds of fluids: • liquid, gas, steam (incl. superheated, super critical point), two-phase
state
• currently 29 different fluids
• user defined fluid mixtures
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How does TDT2 look like ?
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TDT2 User Interface
Initial window after program start:
start a “New project”,
“Open” an existing project,
open one of the “Examples”, which are part of the installation, or
open the “Manual”.
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On the left hand side of the window the entire project information is listed in a tree structure.
The right hand side has three areas: the action toolbar (with buttons to start calculations and,
the notebook (containing the overview, graphs and diagrams) and the calculation output at
the bottom.
TDT2 Main Window Structure
tree structure action toolbar
notebook containing
overview and graphs
calculation output
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TDT2 Detailed Part Information
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TDT2 Ease of Input
Currently, 9 different types of parts are available in TDT2:
Compressor: component to increase the pressure of a compressible fluid
Pump: component to increase the pressure of an incompressible fluid
Turbine: component to expand either compressible or incompressible fluids;
this component also covers so-called expanders
Combustor: component to calculated simple combustion of gases
Condenser: cools a fluid, so that liquid state is reached at the outlet
Heat exchanger: general component to put heat into the fluid or to cool a fluid
Pressure loss element: component to consider pressure losses e.g. in pipes
Process branch: splitting and mixing of fluid flows
Interface: used to create a connection between 2 heat exchangers
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TDT2 Available Fluids
Applicable various kinds of fluids
The current version of TDT2 can calculate the properties of 29 different fluids
in the liquid, gas (super-heated and super-critical) and two-phase state.
◦ pure fluids:
Air (as a pure fluid)
Water (H2O)
Steam (H2O)
Carbon monoxide (CO)
Carbon dioxide (CO2)
Hydrogen (H2)
Oxygen (O2)
Nitrogen (N2)
Ammonia (NH3)
◦ inert gases:
Helium (He)
Neon (Ne)
Argon (Ar)
Krypton (Kr)
Xenon (Xe)
◦ alkanes:
Methane (CH4)
Ethane (C2H6)
Propane (C3H8)
Butane (C4H10)
Isobutane (C4H10)
Pentane (C5H12)
Hexane (C6H14)
◦ aromatic hydrocarbons:
Toluene (C7H8)
◦ refrigerants: R11 (Trichlorofluoromethane, CCl3F)
R12 (Dichlorodifluoromethane, CCl2F2)
R123 (Dichlorotrifluoromethylmethane, C2HCl2F3)
R1234YF (Tetrafluoropropylene, C3H2F4)
R134 (Tetrafluoroethane, CH2FCF3)
R245CA (Pentafluoropropane, C3H3F5)
R245FA (Pentafluoropropane, C3H3F5)
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TDT2 Definition of Mixtures
Definition of mixtures available, e.g.:
• furnace gases
• alkane mixtures
• special gas compositions
Fluids are defined by selecting
components and assigning volume or
mass fractions and additional humidity.
3 fluid mixture types:
• Dry mixtures: no water content
• Humid mixtures: water content, with
condensation calculation
• General mixtures: water allowed, no
condensation is calculated
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How does TDT2 work ?
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Calculation of change of state
(compression & expansion)
Polytropic head:
Outlet temperature:
Critical point
11n
nRTZy v
v
n
1n
v
v11p
Various states possible in TDT:
・liquid
・vapor (super-heated, super-critical)
・two-phase state
T
T
n
1n
12 TT
TDT2 Calculation of Change of State
Isentropic volume coefficient:
Isentropic temperature coefficient:
Polytropic volume coefficient:
Polytropic temperature coefficient:
s
vv
p
p
vk
s
T
pT
Tp
1
1k
T
T
p
p
v
v
v
v
k
1k1
k
1k
n
1n
T
T
p
p
pT
T
k
1k1
c
ZR
n
1n
with pressure ratio , real gas coefficient Z,
specific heat cp and polytropic efficiency p
Reference: K. H. Lüdtke: “Process Centrifugal Compressors – Basics, Function, Operation, Design, Application”, Springer-Verlag Berlin Heidelberg, Germany, 2004
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High calculation accuracy
Entropy Differences of a Real and Isenthalpic Change of State**
** D. Bohn/H.E. Gallus , Energy Conversion Machinery
• change of state in each component is divided into 100 steps
• real gas properties determined in each step
TDT2 High Calculation Accuracy
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TDT2 Visualized Output
Thermodynamic diagrams
• h-s diagram: Enthalpy over Entropy
• p-s diagram: Pressure over Entropy
• T-s diagram: Temperature over Entropy
• p-h diagram: Pressure over Enthalpy
• p-T diagram: Pressure over Temperature
Q-T diagrams
• Evaluation of heat transfer in interfaces
• Inlet & outlet temperatures
• Pinch point determination
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TDT2 Example of Properties Table (Air)
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TDT2 – Features Summary
Real gas properties
29 fluids (e.g. air, steam, CO2, hydrogen, helium, argon, methane, ethane, refrigerants)
Consideration of changing properties during compression / expansion
Export of properties into tables
User-defined fluid mixtures
Implemented components
Compressor
Pump
Turbine
Combustor
Condenser
Few input parameters necessary
Efficiency (polytropic or isentropic)
Outlet pressure (as ratio or fixed)
Leakage (absolute or relative)
Pressure loss (absolute or relative)
Combined cycles
Interaction of energy conversion cycles with different fluid: CCGT, ST+ORC, …
Thermodynamic diagrams & QT-diagrams
Heat exchanger
Pressure Loss
Process Branch
Interface
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Examples
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TDT2 – Examples
Combined Cycle Gas & Steam
CO2 Compression with Intercoolers
Organic Rankine cycles
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TDT – Combined Cycle Gas & Steam
T-S Diagram QT Diagram
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TDT – CO2 Compression with Intercooling
P=36.2 MW
P=31.3 MW
4 Compression steps 8 Compression steps
Comparison: 8 vs. 4 Compression steps
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solar thermal industrial waste
heat geothermal
combined electricity
production
Organic Rankine Cycle
• Process design
• Fluid study
• Process optimization
• Design parameter
TDT - ORC design
Different application areas require individual process design,
parameter studies, analyses of fluid variations, …
efficient and fast thermodynamic process
configuration and calculation of ORC’s
consideration of real gas properties of various fluids
evaluation of state variables
database of fluid property tables
TDT
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TDT2 – Example: Helium & ORC Combined Cycle
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TDT2 - ORC process configuration and parameter study
Example: Process configuration for industrial waste heat utilization
design of multiple types of processes within
one file for study of various parameters or
fluids
T-s, h-s, p-T, etc. diagrams
definition of component efficiencies, pressure
losses, leakage, …
inlet/outlet state variables and component
specific results
definition of boundary
conditions as
transferrable heat, upper
and lower temperature
ranges, etc.
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TDT2 – combined cycle configuration for ORC
Example: Combined cycle configuration of recuperated air turbine with water cooled
intercooler and ORC with isobutane as working fluid
Q-T-diagram of heat
exchanger interfaces
T-s-diagram for
each process
Evaluation of
- required water mass flow for intercooler
- configuration of ORC cycle for waste
heat utilization of air turbine
- parameter study of air cycle and ORC
for highest efficiencies and/or highest
power output
- Q-T-diagrams for heat exchangers
- generate thermodynamic state variables
for component design consideration
Process chart
(e.g. for presentation)
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Thank you very much for your attention!
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