1. Valorisation of Low-Grade Waste Heat
Vision: No useful heat flow without use!
Felix Ziegler | Institut für Energietechnik

2. Valorisation of Low-Grade Waste Heat
Options
Absorption cooling
Steam jet cycle
Honigmann cycle
Efficiency, and cost
Felix Ziegler | Institut für Energietechnik

3. Temperature of heat flowin
out
Temperature of heat flow
upgraded: T3=120°C
source: T2=80°C
work: T→∞
cold: T0=5°C
ambient: T1=35°C
# # # # #5
High source: T4=180°C

4. Temperature of heat flowin
out
Temperature of heat flow
upgraded: T3=120°C
source: T2=80°C
work: T→∞
cold: T0=-150°C
ambient: T1=35°C
High source: T4=180°C
# # # # #5

5. Single-effect absorption chiller Drive Heat sink Cold Heat sink
Cold is produced from heat

6. Nominal cooling capacity 50kW

7. Variation of driving heat @ tsink=30°C, Vsink=3,8l/s, tcold=21/16°C
Driving temperature in [°C]
0,9 l/s
0,6 l/s
0,3 l/s
0,1 l/s
Cooling capacity [kW]
40K
Temperaturspreizung um Ein/Austritt ergänzen

8. Control: Minimisation of auxiliaries
Seasonal Energy Efficiency Ratio:
Control strategy
SEERel
SEERth
#1: Classic drive (Temperature) 13
0,75
#2: Heat sink
(Temperature and flow rate) 19
#3: Drive 14
#4: Combination
(#2+#3) 22

9. „Honigmann“ cycle: storage and conversion of low-grade heat
Pressure
Vapour pressure depression
„mechanical potential“
Water
Aqueous Solution
Liquid-Vapour-Equilibrium
Temperature

10. pressure
temperature
Discharging (work!)
pressure
temperature
Charging (Heat!)

11. Honigmann fireless locomotive (1883)
Quelle: Mähr, Vergessene Erfindungen
Honigmann fireless locomotive (1883)

12. Temperature of heat flowin
out
Temperature of heat flow
upgraded: T3=120°C
source: T2=80°C
work: T→∞
cold: T0=5°C
ambient: T1=35°C
# # # # #5
High source: T4=180°C

15. Valorisation of Low-Grade Waste Heat
There are many challenging / promising options
Efficient heat transfer is key to implementation
Felix Ziegler | Institut für Energietechnik

16. Steam ejector cycle Q Boiler Pump Condenser Ejector Throttle2 1
Boiler
Steam ejector cycle
Pump
Condenser
Ejector
Throttle
Evaporator

17. Steam jet cycle exhaust hx CAC RHX compressor turbine
combustion engine
Steam jet cycle
compressor
turbine
exhaust hx
CAC
RHX

19. Rückkühlvariationen (Biene) @ t_FW=90°C, m_FW=0,9kg/s, t_KW=21/16°C
3,8 l/s
2,0 l/s
1,5 l/s
Cooling capacity [kW]
Phydraulic = nominal
=100%
1,0 l/s
Kann entfallen!
Phydraulic = 1/64*nominal
= 1,5%
Heat sink temperature, inlet [°C]

21. Vorteile des Prozesses
Flexible Be- und Entladung
Nutzung von Abfallwärme
Keine Selbstentladung

22. Single-effect absorption chiller
In the Regenerator G it is regenerated, consuming the driving heat.
The absorbed refrigerant is vaporised again.
A solution circulates between absorber A and regenerator G.
Single-effect
absorption chiller
In the absorber it absorbs refrigerant vapour, rejecting heat.

23. The refrigerant is liquefied in the absorber, rejecting heat...

24. The refrigerant is liquefied in the absorber, rejecting heat...
The vapour flows to the absorber, again.
...and is vapourised again in the evaporator, consuming heat (producing cold).