HOT|COOL NO. 4/2019 - "Components"


The intelligent and controllable bypass solution will enable the district energy operator to reduce the temperature in the network, improve pump efficiency and save energy. Providing temperature control and several pressure measurements, it is built on exactly the same principles as the Flowguard – battery operated with LPWAN technology, and easily retrofitted into existing bypass units and substations. Again, the need for a battery-operated solution complicated the development process. The traditional mechanical thermostats you find in a bypass had to be replaced by an electronic one – once again with minimal use of battery power. Developing this thermostat was a difficult and time-consuming task, which required close cooperation with friends in the district energy sector.

It became clear that the controller only needed to transmit very small data packages regarding operational conditions and receive even smaller data packages in order to control the flow, and only at certain intervals. This is in fact the case with many IoT solutions. This meant that narrowband technology (LPWAN) would be ideal for our purposes, and as the Sigfox network specializes in IoT solutions with many devices spread over a large geographic area with limited and infrequent message needs, it was the logical choice. 10-YEAR BATTERY LIFE The original intent was to use a pressure independent control valve with 5.0 mm stroke due to its high flow capacity. However, it soon became clear that this stroke length would place much too high a strain on battery life. It was replaced by a 2.5 mm stroke valve, which meant a trade-off where high precision - which is not crucial in this solution – was partly sacrificed for long battery life. Another draw on battery life would usually be the actuator, but since the controller is more or less an open or close component, and since the valve only draws battery from it, when it is in motion, the motoric actuator for the PICV (pressure independent control valve) will have very low impact on battery life. With the narrowband technology combined with a short stoke valve and ultra-low consumption by the actuator, it was possible to generate a battery life on the controller of up to 10 years, while keeping the device small and discreet enough that it can easily be retrofitted into the consumers’ existing heat interface units. Now, two years later, Naestved Fjernvarme has installed 200 IoT units, and has shared valuable experiences about the installation process, which will benefit other district heating operators. IoT solutions will save manpower in the long run, but companies still need to gain access to the HIU’s to install them. However, as Naestved Fjernvarme was quick to discover, much preparation can take place in their own workshop, thereby limiting the time that technicians must spend in the field. The company is now about to start analyzing all the new available data. BYPASS IOT CAN IMPROVE EFFICIENCY One thing often leads to the next, and it soon made sense to turn the first IoT product into an IoT Bypass solution which allows district energy operators to monitor their network and ensure that the pipeline is kept warm during the non-heating season. Most installations today are static and non-controllable, which leads to unnecessary heat loss from the district heating network.

However, after months of trial and error, this IoT bypass solution now has an expected battery life of up to five years.

A district energy network with two-way IoT communication.

CLOUD-BASED SOLUTION Information is worthless unless you can access and analyze it. Therefore, these new IoT components are monitored and operated via a cloud-based dashboard, the Flowcloud, which will provide district energy operators with one central access point to all units from their desk at the office or while they are in the field via a mobile phone or tablet. The solution has also been designed for maximum flexibility regarding operational data via API’s to third party control systems. Some complex IoT solutions tend to be quite proprietary, but the approach should be that the data belongs to the customer. We are very happy to offer them a platform solution, which is easy and simple to operate, if they do not have a large setup. Have they already gone into digitalization and built up a platform, then of course that is where data must be provided, adding value for the district energy operator.

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