Types of chillers
LiBr (lithium bromide) chillers are used to generate low temperatures by means of heat. The electricity consumption is usually less than 0.5% of the cooling capacity.
Single-stage chiller
This type of chiller is mostly used with driving temperatures from about 80°C and allows cooling for air conditioning using heat sources such as district heating or solar collectors.
If the driving energy has a low temperature, such as district heating with summer temperatures of flow = 70°C, return = 55°C, the use of a special-purpose chiller should be considered.
Technical data (guideline values)
Driving temperature
(generator)
Flow: 70–100°C
Return: approx. 10 K lower
Medium temperature
(absorber + condenser)
Return: max. 35°C
Flow: approx. 10 K lower
Low temperature
(evaporator)
Return: 6–8°C
Flow: 5–10 K higher
COP
(COP = Q useful / Q input)
approx. 0.7
Driving temperature
(generator)
Flow: 70–100°C
Return: approx. 10 K lower
Medium temperature
(absorber + condenser)
Return: max. 35°C
Flow: approx. 10 K lower
Low temperature
(evaporator)
Return: 6–8°C
Flow: 5–10 K higher
COP
(COP = Q useful / Q input)
approx. 0.7
Double-stage chiller
The advantage of this chiller type is that twice the cooling capacity and thus twice the COP can be achieved with the same driving power. A driving temperature of at least 140°C is required in this case.
Historically, this was the most commonly used type of chiller when there was no electricity available for cooling.
Technical data (guideline values)
Driving temperature
(generator)
Flow: 140–170°C
Return: 10–15 K lower
Medium temperature
(absorber + condenser)
Return: max. 35°C
Flow: approx. 10 K lower
Low temperature
(evaporator)
Return: 6–8°C
Flow: 5–10 K higher
COP
(COP = Q useful / Q input)
approx. 1.4
Driving temperature
(generator)
Flow: 140–170°C
Return: 10–15 K lower
Medium temperature
(absorber + condenser)
Return: max. 35°C
Flow: approx. 10 K lower
Low temperature
(evaporator)
Return: 6–8°C
Flow: 5–10 K higher
COP
(COP = Q useful / Q input)
approx. 1.4
Chiller for low driving temperature
This chiller type is designed for very low temperatures on the driving energy side. They are used, for example, to allow the heat from district heating to be used as the driving energy source despite low network temperatures in summer.
Specification (example)
Driving temperature
(generator)
Flow: 75°C
Return: 55°C
Medium temperature
(absorber + condenser)
Return: 33°C
Flow: 28°C
Low temperature
(evaporator)
Return: 14°C
Flow: 7°C
COP
(COP = Q useful / Q input)
approx. 0.55
Driving temperature
(generator)
Flow: 75°C
Return: 55°C
Medium temperature
(absorber + condenser)
Return: 33°C
Flow: 28°C
Low temperature
(evaporator)
Return: 14°C
Flow: 7°C
COP
(COP = Q useful / Q input)
approx. 0.55
