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The BTES 1.0 templates are divided into different types of regime temperature combinations for heating and cooling end-units. To clarify this aspect the different templates are the following.

  • LT heating + HT cooling

  • HT cooling + HT and LT heating separate

  • HT cooling + HT and LT heating together

  • LT heating + LT and HT cooling separate

  • LT heating + LT and HT cooling together

  • HT and LT heating separate + LT and HT cooling separate

  • HT and LT heating together + LT and HT cooling separate

  • HT and LT heating separate + LT and HT cooling together

  • HT and LT heating together + LT and HT cooling together

LT heating + HT cooling

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Working principle

The working principle of a geothermal system is divided into two main operating conditions, winter and summer. Of course, if there is both heating and cooling demand at the same time, both conditions are active.

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The template is standardised with a boiler and a chiller, but it can easily be removed if it's not required. More information on BTES, heat pump, boiler and dry coolers can be found in:

BTES 1.0

Heat pump

Condensing boiler

Ambient exchange

Controls

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Almost everything in the system is connected to the main programmable controller.

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As a default, the controller will only make sure the basic working principle works, which is explained in the previous chapter “Working principle”. This means the user can delete every aspect that’s not necessary for their specific application, like the dry coolers, boiler, chiller, etc.

The following settings can be changed by the user in the programmable controller:

  • FlowrateHeatingLTmin = 1;
    (= minimal flow rate for LT heating when heating demand is considered, in m³/h)

  • FlowrateCoolingHTmin = 1;
    (= minimal flow rate for HT cooling when cooling demand is considered, in m³/h)

  • FlowrateHysteresisPercentage = 20;
    (= hysteresis percentage above and below the minimal flow rate for heating and cooling, in % )

  • TempBTESCold = 4;
    (= minimal temperature of the BTES system, in °C)

  • TempBTESHot = 18;
    (= maximal temperature of the BTES system, in °C)

  • TempBTESHysteresis = 2;
    (= hysteresis temperature above and below the minimal and maximal temperature of the BTES system)

  • StorageHotTopHPon = 60;
    (= temperature at the top of the hot thermal store when the HP is activated, in °C)

  • StorageHotBottomHPoff = 60;
    (= temperature at the bottom of the hot thermal store when the HP is deactivated, in °C)

  • StorageColdTopHPon = 2;
    (= temperature at the top of the cold thermal store when the HP is activated, in °C)

  • StorageColdBottomHPoff = 2;
    (= temperature at the bottom of the cold thermal store when the HP is deactivated, in °C)

  • TempHPcondenserHot = 80;
    (= maximal temperature as safety for the HP, in °C)

  • TempHPevaporatorCold = -5;
    (= minimal temperature as safety for the HP, in °C)

  • FlowrateHPevaporatorMin = 45;
    (= minimal flow rate required as safety for HP, in m³/h)

  • FlowrateHPcondenserMin = 15;
    (= minimal flow rate required as safety for HP, in m³/h)

  • HPdelay = 5;
    (= time delay between deactivation and activation of HP, in min)

  • TempBTESColdWithdrawMin = TempCoolingReturn - 2;
    (= minimal temperature of the BTES system for activation BTES pump, in °C)

  • TempBTESColdWithdrawMax = TempCoolingReturn - 1;
    (= maximal temperature of the BTES system for deactivation BTES pump, in °C)

There are other setpoints at the cooling and heating end units (which are also an input for the programmable controller) which can be changed by the user. The setpoints are visualised with a “C” base circuit. More information on control base circuits can be found in Control library.

Above mentioned setpoints are necessary for the basic working principle. More settings are available but are only needed if some of the optional or regeneration strategies are activated. The activation can be done by changing the “0” to a “1” for the following strategies.

  • AEHotReleaseOn = 0;
    (= activation for the dry cooler at the condenser side of the heat pump to release the excess heat, this also activates the ability of the heat pump to directly deliver cooling to the system)

  • AEColdReleaseOn = 0;
    (= activation for the dry cooler at the evaporator side of the heat pump to release excess cooling)

  • AEColdSupplyOn = 0;
    (= activation for the dry cooler to supply cooling available in the ambient air to the building)

  • HPDirectHeatingCoolingOn = 0;
    (= activation for the heat pump to directly and simultaneously deliver the produced heating and cooling to the building)

  • AEColdDepositOn = 0;
    (= activation for the dry cooler to deposit cold into the BTES system)

  • AEColdWithdrawOn = 0;
    (= activation for the dry cooler to withdraw cold from the BTES system)

  • HPActiveColdDepositOn = 0;
    (= activation for the heat pump to actively deposit cold into the BTES system with help from the AEHotRelease)

  • BTESColdDepositLimitationHeatingOn = 0;
    (= activation for the limitation of depositing cold into the BTES system in heating mode)

  • BTESColdDepositLimitationHeatingCoolingOn = 0;
    (= activation for the limitation of depositing cold into the BTES system in combined heating and cooling mode)

  • BTESColdWithdrawLimitationCoolingOn = 0;
    (= activation for the limitation of withdrawing cold from the BTES system in cooling mode)

  • BTESColdWithdrawLimitationHeatingCoolingOn = 0;
    (= activation for the limitation of withdrawing cold from the BTES system in combined heating and cooling mode)

Depending on the strategy the user wants to apply, one or more aspects should be activated. Check which components are active in every desired strategy and activate all these components with the settings above.

The specific settings for the different strategies are the following:

  • TempHPColdSupplyMin = CoolingSP - 1;
    (= minimal temperature in the cold thermal store for activation HP active cold supply)

  • TempHPColdSupplyMax = CoolingSP +1;
    (= maximal temperature in the cold thermal store for deactivation HP active cold supply)

  • StorageHotMiddleAEHotReleaseOn = 60;
    (= temperature at the middle of the hot thermal store when the dry cooler hot release is activated, in °C)

  • StorageHotTopAEHotReleaseOff = 60;
    (= temperature at the top of the hot thermal store when the dry cooler hot release is deactivated, in °C)

  • StorageColdMiddleAEColdReleaseOn = 2;
    (= temperature at the middle of the cold thermal store when the dry cooler cold release is activated, in °C)

  • StorageColdTopAEColdReleaseOff = 2;
    (= temperature at the top of the cold thermal store when the dry cooler cold release is deactivated, in °C)

  • BTESColdDepositLimit = 9999999999999999;
    (= limited energy amount for cold deposit going in the BTES system, if this amount is crossed cold deposit won’t be allowed until the following year, in kWh)

  • BTESColdWithdrawLimit = 9999999999999999;
    (= limited energy amount for cold withdraw going out of the BTES system, if this amount is crossed cold withdraw won’t be allowed until the following year, in kWh)

  • AEColdDepositLimit = 9999999999999999;
    (= limited energy amount for cold deposit by the dry cooler, if this amount is crossed the dry cooler won’t be allowed to deposit cold anymore until the following year, in kWh)

  • AEColdWithdrawLimit = 9999999999999999;
    (= limited energy amount for cold withdraw by the dry cooler, if this amount is crossed the dry cooler won’t be allowed to withdraw cold anymore until the following year, in kWh)

  • HPActiveColdDepositLimit = 9999999999999999;
    (= limited energy amount for active cold deposit by the heat pump, if this amount is crossed the heat pump won’t be allowed to actively deposit cold anymore until the following year, in kWh)

Notices/Remarks

  • The system can be further optimised by doing sensitivity studies. For instance, a sensitivity study can be done for the size of the storage vessel or the thermal power of the HP and/or BTES system. To change the thermal power, the user should change the power spread found in the hybrid production configuration BC and/or the production BC’s. More information about hybrid production configurations and production BC’s can be found in Hybrid production Heating, Production Heating, Geothermal energy storage, Ambient exchange.

  • The user can change the design temperatures, thermal power, end units, etc. Keep in mind that the controls have to be changed as well. This can be done by changing the “settings” in the programmable controller which are listed in the top of the code. After changing the settings, the correct operation has to be checked again. The user should only change the “settings” and nothing else in the code to make sure the correct control strategy is still valid. If the user wants to change the control strategy, please contact our support team.

  • If the user changes the power of the end-units the thermal capacity of the boiler, chiller and heat pump doesn’t change automatically. The user should implement a correct capacity corresponded with the thermal power of the production units.

  • There are default COP and power tables for the heat pump, but these can be changed by the user.

  • The user can alter the template by deleting everything that’s not applicable in their case, but the basic components mentioned in the chapter “Working principle” still have to be there. The basic components are needed to make sure the control strategy is still valid. If the user deletes parts of the system, the control lines should be deleted as well. Otherwise, the system will give an error saying there are nodes not connected.

Geothermal energy storage systems are complex. If there are any more questions, please contact our support team.

HT cooling + HT and LT heating separate

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This template is the same as the previous template “BTES 1.0 - LT heating + HT cooling” except for the additional HT heating. The HT heating required is only supplied by the boiler, not by the heat pump.

HT cooling + HT and LT heating together

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This template is the same as the previous template “BTES 1.0 - LT heating + HT cooling” except for the additional HT heating. The HT heating required is both supplied by the heat pump as the boiler. This template is similar to the previous template “HT cooling + HT and LT heating separate”. The most optimal configuration between these two depends on the situation and should be simulated. If the return temperature of the HT heating is low enough for the heat pump, it might increase the contribution of the heat pump by combining the HT and LT heating.

LT heating + LT and HT cooling separate

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This template is the same as the previous template “BTES 1.0 - LT heating + HT cooling” except for the additional LT cooling. The LT cooling required is only supplied by the chiller, not by the BTES system or heat pump.

LT heating + LT and HT cooling together

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This template is the same as the previous template “BTES 1.0 - LT heating + HT cooling” except for the additional LT cooling. The LT cooling required is both supplied by the BTES system as the chiller. This template is similar to the previous template “LT heating + LT and HT cooling separate”. The most optimal configuration between these two depends on the situation and should be simulated. If the return temperature of the LT cooling is high enough for the BTES system, it might increase the contribution of the BTES by combining the LT and HT cooling.

HT and LT heating separate + LT and HT cooling separate

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This template is a combination of “HT cooling + HT and LT heating separate” and “LT heating + LT and HT cooling separate”.

HT and LT heating together + LT and HT cooling separate

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This template is a combination of “HT cooling + HT and LT heating together” and “LT heating + LT and HT cooling separate”.

HT and LT heating separate + LT and HT cooling together

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This template is a combination of “HT cooling + HT and LT heating separate” and “LT heating + LT and HT cooling together”.

HT and LT heating together + LT and HT cooling together

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This template is a combination of “HT cooling + HT and LT heating together” and “LT heating + LT and HT cooling together”.