Internal energy and pressure by means of the heat pump

Thomas Bauer, Dorle Lohn, Benjamin Best, Philipp Schneider
Status: Apr 2023

Although heat pumps have been used for a long time, often when the heat pump is mentioned as a heating system, the question arises "What do you heat with then?". If drilling is done in depth and thus the heat of the earth is used, it seems relatively plausible to many people where the energy comes from, even if in some cases only 20°C warm water is tapped here, which is indeed too little for a heating system that requires at least 40°C. However, if the air is used as a heat reservoir, the astonishment is often very great. Because actually the question arises:

"How does the heat pump manage to transport heat from cold to warm?"

In this context, the teaching unit aims to teach the traditional contents "change of internal energy due to work and heat", "introduction of pressure" and "heat transport" on the basis of the heat pump, thus not wasting any time.


Heat, heat flow and insulation

20% of final energy consumption in Germany is required for heating. Thus, a heat turnaround is essential for a functioning energy turnaround.

Heat theory is a traditional part of physics lessons

With the help of this worksheet, the physical quantity "heat" is introduced, heat transport and heat insulation are addressed, and at the same time an understanding of the importance of the heat transition is established among the students.

>>Worksheet: Heat, heat flow and insulation (docx/pdf)


Some things work with pressure - The secret of the heat pump

How can the heat pump heat the warm house with the cold outside air?

This is the question many people ask when they learn about a heat pump as a heating system.

The aim of this worksheet is to use this question to introduce the physical quantity of pressure as a measure of the "compressed nature of the air".

>>Worksheet: Some things work with pressure - The secret of the heat pump (docx/pdf)


Heat pump: how to heat with the cold air?

The heat pump is essentially based on two principles:

Heat always flows from the place of higher temperature to the place of lower temperature
By changing the pressure, the temperature changes
These two principles were introduced using the previous worksheets and are now linked so that the fascinating technology of the heat pump becomes understandable and the students realize how energy can be obtained by using this technology.

>> Worksheet: how to heat with the cold air? (docx/pdf)


Heat pump and refrigerator: how to use condensation!

In reality, just like the refrigerator, the heat pump naturally uses phase transitions. This worksheet is designed to use the principles developed in the previous worksheet and now look at the heat pump with phase transitions.

>> Worksheet: Heat pump and refrigerator: how to use condensation! (docx/pdf)


Geothermal energy and heat pumps - It's getting hot in here

As a conclusion of this unit, it is now balanced how much energy can be gained by geothermal energy and heat pumps.

By simple estimations of the annual performance factor, the current heating demand and possible insulation measures, one learns that one could gain approx. 8-9 kWh per day and person.

>> Worksheet: Geothermal energy and heat pumps - It's getting hot in here (docx/pdf)


Here you will find experiments for your lessons on geothermal energy.