Tutorial 2 – Heat pumps

 

Overview

This tutorial focuses on the modelling of heat pumps and will show you how to implement the following features in your energy model:

à Multiple temperature level heat demands

à Multi-input technologies through different representations of heat pumps/chillers

à Technology with multiple functions through the modelling of a reversible heat pump

 

The energy hub diagram will look like the following:

 

 

 

Step 0 – Getting started

The procedure here is the same as for Tutorial 1. You can name the project, Analysis and the scenario, Tutorial 2, Heat pump potential and General HPs respectively.

 

 

Step 1 - Hubs

The hub section allows you to create different energy hubs that will contain multiple energy conversion, storage and/or network technologies. This tutorial contains a single hub.

à Select Add New Hub, name it (e.g. Campus) and press Add.

 

 

Step 2 – Energy carriers

à Select Add New Energy Carrier to define an energy carrier.

à Assign a Type and Name to each energy carrier that you create and Add it.

Find below the list of energy carriers used here.

Type

Name

Custom name

Thermal Energy

Custom

Lake

Thermal Energy

Heat 70-80°C

-

Thermal Energy

Heat 30-40°C

-

Thermal Energy

Heat 10-20°C

-

Thermal Energy

Cooling

-

Thermal Energy

Heat Ambient

-

Electrical Energy

Electricity

-

Other

Custom

Dummy

 

The dummy variable is a virtual EC and will be useful for Step 6.2.

à Select Next to move to the Energy Demands section.

 

 

Step 3 – Energy Demands

à Press Add New Energy Demand to add an electricity or heat demand.

à Select the hub that requires the energy (only one hub here to choose from). Then select the energy carrier related to the demand and name this energy demand.

Here again the profiles will be chosen from the database.

à Press Select From Our Database and select the following energy demands:

·       Heat 70-80°C: MFH-Full_Retrofit-144299-Heat

·       Heat 30-40°C: MFH-Full_Retrofit-144299-Heat

·       Cooling: MFH-Full_Retrofit-144299-Cooling

à Give them a scaling factor of 100 for Heat 70-80°C and Cooling and one of 50 for Heat 30-40°C.

The electricity demand of the hub is ignored. The electricity needed to make the heat pump work is determined by the optimization.

à Select Next to move to the On-Site resources section.

 

 

Step 4 – On-site resources

This tutorial uses two On-site resources: cold water from the Lake and ambient heat from outside (called Heat Ambient here).

1.       Lake as an on-site resource

à Select Add New Other Resource to add the amount of water available from the lake.

à Select the energy carrier Lake and the energy hub created before. The available resource has two limits Total Annual Energy Available On-site [kWh/y] and Maximum Hourly Energy Available On-Site [kWh/h]. For simplicity, leave those boxes free.

2.       Heat Ambient as an on-site resource

à Repeat the procedure for the EC Heat Ambient.

 

 

Step 5 – Import & Exports

Like in Tutorial 1, you will need to import Electricity:

Graphical user interface, text, application

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No exports are needed in this tutorial.

 

 

Step 6 – Supply Technologies

Heat pumps and heat exchangers are different types of conversion technologies. The following steps give more details on how to implement them.

 

Step 6.1 – Multi temperature levels and heat exchangers

As seen in step 0, the tutorial has 3 energy levels: cooling, heat 30-40°C and heat 70-80°C.  Since the heat is assumed to be dissipated and for the system to make better use of the energy, model the following two virtual heat exchangers.

à Select Add New Conversion Technology, fill in the boxes like given below. Don’t forget to tick the box of Virtual Technology:

1.       Heat exchanger for MT -> LT

2.       Heat exchanger for HT -> MT

Furthermore, the cold water from the lake can be directly taken from the lake to provide cooling. This is again done by a heat exchanger.

à Select Add New Conversion Technology and fill in the boxes like given below:

 

Step 6.2 – General heat pump/chiller

The general model of a heat pump or a chiller is the same. It has as input Electricity and a Low Temperature (LT) Heat and as output Heat at a higher temperature (MT or HT):

The main difference of a chiller and a heat pump lies in the aim of their usage. The heat pumps goal is to provide heat while the chiller is there to provide cooling. However, since the technology is the same, a chiller will still have the LT heat as its input. The application of heat pump and chiller is a bit different.

1.       Application of a heat pump

à Select Add New Conversion Technology and fill in the boxes like in the following image:

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Description automatically generated

The heat pump to be modelled is an Air Source Heat Pump and will thus need ambient heat as an input. The diagram for this heat pump can be represented as such:

Thus, the function has the following parameters:

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Description automatically generated

2.       Application of a chiller

The chiller implementation is a bit trickier to get one’s head around. The diagram is the following:

It shows that even though the chiller takes Heat (LT) as an input, it’s aim is to produce cooling which is represented by a heat exchanger with 0 input and 2 outputs which has no costs.

à Select Add New Conversion Technology and give it the following parameters:

à Add the following virtual heat exchanger:

Next to chillers working with electricity, you can also have an absorption chiller which works with three heat sources.

à Select Add New Conversion Technology and give the following parameters to model an absorption chiller:

 

Step 6.3 – Implementing a multi-input technology + technology with multiple functions

Reversible heat pumps have a cooling and a heating function.

à Select Add New Conversion Technology and give the heat pump the following characteristics:

The primary energy input is chosen to be electricity. Thus, the efficiency equals the COP that is assumed to be 4 (i.e. 400%).

à Select New Function to add the cooling function with the parameters:

 

 

Step 7 – Network Technologies and Links

This tutorial has only one hub and won’t need any links. See Tutorial 3 for an example with multiple hubs.

à Select Next to move to Other.

 

 

Step 8 – Other

This section allows to include the current interest rate in [%] to the model. Set it to 2%.

 

 

Step 9 – Review

Look at the review section to have an overview over the entire scenario specification and edit a section if needed.

à Select Finish Specification & Prepare for Execution to get to the execution of the model.

 

 

Step 10 – Execution & Results

Next to the Setup section you can find the Execution section where you select the scenario to be optimized, the two objectives the optimization should be based on and finally the number of points wanted in the pareto front.

à Select Execute to start the optimization.

à Once you receive an email that the optimization is completed, Go to the Results section and Select Download to go through the results of the optimization.

à Click on View results to open the dashboard of your optimal design