A guideline for industrial heat pumps adapted to district heating networks

Client	Stadtwerke Lemgo, Germany	Hall AG, Austria	Stadtwerke Heidelberg, Germany	Blockheizkraftwerks, Träger- und Betreibergesellschaft mbH Berlin (BTB), Germany
Supplier of heat pump	Global Engineering Alliance (GEA), Germany	Ochsner Energietechnik, Austria	Johnson Controls International, Denmark	Friotherm, Switzerland
Type of heat pump	GEA RedAstrum		Sabroe HeatPac	Unitop 28/22CY
Total thermal capacity of heat pump	Two units of 1.2 MW each	Four units of 300 kW to 1.1 MW modulating	Three units of 1.35 MW	Two units of 3.5 MW each
Year of commissioning	2019	2021	2023	2023
Type of compressor	Screw	Screw	Piston	Two-stage turbo
Type of refrigerant	R717 (ammonia)	R1234ze	F717 (ammonia)	R1234ze
Type and temperature of heat source	Sewage water at 7 to 22 °C	Exhaust gas from boilers	Air of at least 5 °C	River water of at least 8 °C
Temperature level of delivered heat	63 to 82 °C	65 °C	Up to 90 °C	Up to 90 °C

	Type of refrigerant		Climate impact
	Designation	Substance	ODP	GWP100
Natural refrigerant	R717	ammonia	0	0
	R744	carbon dioxide	0	1
	R290	propane	0	3
	R600	butane	0	4
	R600a	isobutane	0	3
Synthetic refrigerants	R1234ze		0	7
	R1234zd		0.00034	4.5
	R1234yf		0	4

Heat source	Typical heat source temperatures	Temperature fluctuations	Typical availability
Ambient air	0 to 40 °C	high	April to September
Surface water (e.g. rivers)	2 to 20 °C	medium	April to October
Ground water	3 to 15 °C	low	all year round
Sewage water	7 to 20 °C	medium	all year round
Geothermal energy	0 to 19 °C	medium	all year round
Waste heat	14 to 50 °C	individual	individual
Flue/exhaust gases	30 to 50 °C	low	individual
PV-Thermal collector field	0 to 35 °C	high	all year round