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

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

Temperature of heat flow in out Temperature of heat flow upgraded: T3=120°C source: T2=80°C work: T→∞ cold: T0=5°C ambient: T1=35°C #1 #2 #3 #4 #5 High source: T4=180°C

Temperature of heat flow in 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 #1 #2 #3 #4 #5

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

Nominal cooling capacity 50kW

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] Dt@40kW=13K 40K Temperaturspreizung um Ein/Austritt ergänzen

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

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

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

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

Temperature of heat flow in out Temperature of heat flow upgraded: T3=120°C source: T2=80°C work: T→∞ cold: T0=5°C ambient: T1=35°C #1 #2 #3 #4 #5 High source: T4=180°C

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

Steam ejector cycle Q Boiler Pump Condenser Ejector Throttle 2 1 Boiler Steam ejector cycle Pump Condenser Ejector Throttle Evaporator

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

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]

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

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.

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

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).