How to optimize cascade couplings for best use of low temperature sources

Date: 03/09/2018

What is the main purpose of the report?
The main purpose was to study parameter variations of cascade couplings of heat pumps used to produce district heating based on low temperature heat sources of 7-23°C. The studies will form a basis for the upcoming demonstration projects at the demo sites in Cool DH.

What are the main findings in the studies?
The main finding is that you achieve the highest performance when similar heat pumps work under similar conditions. This means that each heat pump in the system should work with the same temperature differences on both the hot and cold side. We could also conclude that lower district heating supply temperatures results in higher performance values. This has a significant influence on the heat pump performances making it more feasible for low temperature district heating. Furthermore, a theoretical study of the refrigerants used as working fluid in the heat pumps showed that R717 (ammonia) resulted in the highest performance of the refrigerants investigated.

What happens now?
We will present the results in a workshop, to be held in November within the scope of the Cool DH project. Some of the results will be implemented when designing the heat recovery systems in Lund and Høje-Taastrup.

Read the report

You will find the report under the Report and document section.