Solar Heat Energy Demonstrator

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To Do:

  • Review designs and calculate loads
  • Produce schematic of proposed design
  • Detailed design of pipework and equipment

Aims

The aim of the project is two-fold.

  • Provide better heating for the building using low carbon heat, bringing the building up to a suitable level of heating to be passed on to the next occupants.
  • Conduct detailed tests to work out the best practices and installation choices, to maximise in-use efficiency of CO2 heat pump technology, and work out it's place in the renewables landscape for the future.

Requirements

Following initial site meetings the following requirements have been set:

  • Installation of CO2 air source heat pump(s)
  • Low use domestic hot water
  • Central heating to 10 office spaces
  • Office spaces to be fitted with a selection of heat emitter types
  • System to be flexible enough to allow different heating strategies to be tested
  • System must be of a standard to be handed over to the next building occupants
  • System must allow for the optional use of fan convectors as final stage to heat the main area and lower return temperatures
  • System to be provide real-time operational data and allow details adjustment of settings and controls logic

Documents

Proposed SHED Upgrading Works - first floor layout.pdf Proposed Occupancy Office Layout.pdf LE 155 0 ExistingShed-Ground.pdf LE 155 0 Existing SHED-First (1).pdf P2 04 Existing South & West Elevations (2).pdf P2 03 Existing North & East Elevations (2).pdf

Design Points

The following points have been considered.



  • QAVH connection to buffer store. This arrangement is used to draw heat from the cold part of the buffer for defrost protection.

  • Setting 121 decides secondary control is enabled. We do not need secondary control so it can be left in default setting (off).

  • Trace heating (electrical tape) is used to prevent pipework from freezing as a matter of last resort if the circulation pump should fail for defrosting. We will tie control over this into system.

  • Because of the need for (1) the heat pump defrost circuit to go through the store, and (2) the stability of the output from the heat pump is unknown and could do with some buffering via the top of the buffer store, it will be prudent to fit buffer stores with internal diffuser plates to create chambers to contain turbulence, and maintain stratification.

  • This table shows water quality requirements for the heat pump, and also for a secondary side (not used in SHED). It is important that regular tests are made to ensure this is met. It is also advisable to install water filtration equipment that can maintain these parameters with as little maintenance as possible. Remote monitoring on each of these would be nice.

System Schematic

  • Double-click in the diagram background in order to add a new node there.
  • Add ports to a selected node by clicking the above buttons or by using the context menu.
  • Draw links between ports by dragging between ports.
  • Right-click on a port to bring up menu.


Heating Schematic


Heat Pump Selection

Mitsubishi Electric QAVG 40kW CO2 Air Source Heat Pump

Selection

The selected heat pump is a Mitsubishi Electric QAVG 40kW CO2 Air Source Heat Pump.

Specifically designed for commercial sanitary hot water application, where gas boilers, combined heat and power systems (CHP) or electric water heating have been traditionally utilised, the QAHV provides a low carbon solution for hospitals, hotels, leisure centres and student accommodation. Utilising the natural and stable refrigerant CO2 (R744), the environmentally clean solution enables compliance to strict local planning laws and boosts BREEAM points. Compounded by the increasing decarbonisation of the electrical grid and the UK’s commitment to Net Zero 2050, the QAHV provides a high efficiency, low carbon hot water delivery solution with leaving water temperature up to 90°C.

Documentation

QAHV_6PP_AW_v2
QAHV-N560YA-HPB_Service_Manual
QAHV-N560YA-HPB_Install_Manual
QAHV-N560YA-HPB-PI-SHEET

Technical Specifications

Qavh1.png

Room Controllers

Sontay Smart Room Thermostats with Temperature, CO2, Relative Humidity, PIR and ModBus

Initial requirement is for:

  • temperature, humidity and CO2 sensing.
  • hard wired
  • preferable Modbus RTU / TCP, or BACNET
  • existing units that use 0-10v and resistance can be worked with Sontay GS-CO2-S

Suggest SC-S-403000 with:

  • temperature, humidity and CO2 sensing.
  • PIR sensing
  • Modbus RTU or BACnet
  • 24v dc

Sc-x-download.pdf
Modbus Registers
SC-S Smart Sensor

Domestic Hot Water

The SLIM HIU (Hydraulic Interface Unit)

Hot water to be provided using a SLIM HIU from Thermal Integration.

  • Fully electronic solution with anti-legionella cycle & PC connectivity for set-up and commissioning
  • Calibrated sensors for fast DHW temperature control
  • Eco / Comfort DHW modes for continuous or intelligent pre-heat
  • Compact design - 240mm (W) x 420mm (H) x 90mm (D)
  • Fully insulated compartmentalised casing
  • Stainless steel pipework
  • Open control options
  • RS485 interface
  • Optional primary pump kit Optional 24V
  • DC version
  • Optional security case with integral heat meter, landlord security valve and anti-fraud sealing kit.
  • From the same family of HIUs as the DATA - has the industries best BESA VWART figures of all time


Slimspec1.png


See http://heatweb.co.uk/w/index.php?title=The_SLIM_HIU

Sizing

Bivalent Systems for Heat Networks

The following designs show the impact of a single 40kW heat pump on various numbers of properties. This is unrelated to the SHED, however is shown in order to give the reader a feel for the impact of even a single heat pump on real-world loads.

Each property is 2 bedroom 3 person, and 4kW heating load.

Topping up boilers are included to achieve peak loads.

Caption text
Properties % Heat Pump Design Link
20 x 2B3P 99.9% https://hw7.ddns.net/ui/hndesign?loadCID=QmNg4trTmoxkD35qj4eBWd1exKwKfbVpP3jRNgEQwZn4qB
30 x 2B3P 94.6% https://hw7.ddns.net/ui/hndesign?loadCID=QmXz5H1sdV5F1juQrQc71PLjdWCPWkHhqHkitGbC8o8B9z
40 x 2B3P 83.6% https://hw7.ddns.net/ui/hndesign?loadCID=QmPgBB6jSXehwP2ZYp7LcZNQeEyXggQM4FPgcgdQWQgZVc

Bivalent40kw

Co2graph1.png

This graph shows how the vast majority of load (for 2021) is driven by heat pumps (blue & orange), with boilers (green) used to top up.

Operational Data Policy

This section manages any policies, requirements and plans on data storage, user access, and MQTT permissions.

  • Operational data to be logged in real-time
  • Recent data points stored in controller memory
  • Options to write data logs to hard drive
  • Options to write data logs to IPFS file system (encryption policy to discuss)
  • Use of both crude and fine grained security settings by user, network, device, data type and key (MQTT ACL file functionality)
  • This Wiki project page will detail performance data for as long as SHED is in 'public' mode
  • A Private Wiki will run on the LAN with levels of user access control. This will act as:
    • the primary user interface,
    • storage space for logs locally,
    • documentation repository.
    • backups of controller software (so new controllers can be cloned)
  • VPN access to system
  • SSL https certificates on any exposed portals, and on MQTT services.
  • None of these core functions to require any licences or software costs (just add internet)
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