analysis of thermodynamic processes with full ... of thermodynamic processes with full consideration...

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Analysis of thermodynamic processes

with full consideration of real gas behaviour



• What is TDT 2 ?

• How does it look like ?

• How does it work ?

• Examples

Contents



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 ?



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



How does TDT2 look like ?



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”.



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



TDT2 Detailed Part Information



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



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)



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



How does TDT2 work ?



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



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



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



TDT2 Example of Properties Table (Air)



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



Examples



TDT2 – Examples

Combined Cycle Gas & Steam

CO2 Compression with Intercoolers

Organic Rankine cycles



TDT – Combined Cycle Gas & Steam

T-S Diagram QT Diagram



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



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



TDT2 – Example: Helium & ORC Combined Cycle



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.



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)



Thank you very much for your attention!

analysis of thermodynamic processes with full ... of thermodynamic processes with full consideration...

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