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A TRT and this template have the following principle. A mixing circuit is used production (typically electric) is controlled to make sure the temperature difference between the ingoing and outgoing temperature of the probe is constant (in this case 4 K, the user should change the constant value depending on the executed TRT). A constant volume flow is delivered by the pump, which results in a rather constant thermal power injected into the soil.
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Undisturbed (natural) soil temperature [°C] → Natural soil temperature
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In a TRT the borehole resistance is also typically given and should be recalculated to the heat transfer coefficient of the borehole heat exchanger as follows.
UA-value borehole [W/K] = depth borehole [m] / borehole resistance [m.K/W]
The calculated borehole UA-value should also be implemented and locked by the user.
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If the pressure drop is also given from the test, the KV value can be calculated by clicking on the pencil icon visualised above. After clicking on the pencil icon, a popup window appears. In this popup window, the user can calculate the KV value by entering the pressure drop and the volume flow rate (which is also given by the TRT).
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The user should click on the middle icon with the arrow pointing down in the cloud to export the file. After exporting, the values in the file should be changed with data calculated from the trend function. The trend function starts with a time of 0h, however, the data for the first 12h 24h shouldn’t be used because at this point the behaviour isn’t stationary yet. After changing the data, the user should import it into the software by clicking on the right icon with the arrow pointing up in the cloud and uploading the file.
After the user has successfully imported the data file, the user can compare the simulated soil temperature (green) and the temperature generated from the trend function (redpurple) in 1 graph by plotting them together. In the graph below the BTES system is successfully load matched with the trend function. The load matching should be done by changing the 3 parameters, spoken of earlier.
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However, for a TRT only 1 probe is used to do the test. In a real installation, more probes are typically used wich means these parameters should be scaled accordingly. The way to scale them isn’t always linear. The parameters parameter that should be scaled linearly are:
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is the cold deposit power.
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UA-value borehole heat exchanger
The KV-value of the borehole heat exchanger and the natural soil temperature stays stay the same. The soil start temperature should be set the same as the natural soil temperature.
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