Refrigeration brings life to Chinatown

UK: A bespoke HVACR solution, employing RDM controls and a lower GWP, R404A alternative refrigerant, is providing the idea solution for a thriving Chinese supermarket in London.

The high efficiency customised solution has been installed at the SeeWoo store in the heart of London’s Chinatown. The SeeWoo Group is one of the largest suppliers of oriental foods in the UK with three retail stores, wholesale operations, restaurants and food production factory. SeeWoo’s London store started as a small grocery shop in 1975 and has since grown into a thriving supermarket. SeeWoo increased the size of the supermarket, extending into the adjacent property. Due to building constraints that made the installation of off-the-shelf type systems very difficult, the property had previously never had any form of heating or comfort cooling in its 40 year history.

Expanding its refrigerated offer, SeeWoo also wanted to add fresh meat, fish and live fish tanks. R404A refrigeration units were to be replaced with central plant to cover the entire site.  Priorities of the project included energy efficiency, reliability, low noise, low GWP for future-proofing, ventilation, comfort cooling and heat recovery – all of which had to be delivered without any downtime or closure of the busy trading store. 

Ultra Refrigeration, the award winning Welwyn-Garden-City-based contractor, was selected by the client to provide a bespoke solution. Ultra produced two of its Integrated Power Packs (IPP), both of which are triple-stage externally compounded booster systems with integrated heat recovery. 

Purposefully designed by their CAD engineers, and built on a steel frame, the two packs, heat recovery station, and condenser and servicing platforms were fully assembled ready for crane lifting over the building, and onto the flat roof area to the rear of the premises. Each pack containing four LT, two MT, and one HT compressors, with independent variable speed drives was controlled by advanced custom software, delivering smooth and reliable suction pressures.

The new system employs R449A, the lower GWP, R404A alternative refrigerant, marketed by Chemours as Opteon XP40. Having used it on a number of projects, Ultra says it has found R449A to provide preferable temperatures for heat recovery.

Speed controlled EC fans deliver stable head pressures, varied according to ambient or store conditions for optimum efficiency and heat recovery. Heat from both refrigeration packs is recovered to a water circuit with additional heat top-up from the air source evaporator integral to the dual condenser.

The water circuit, also capable of comfort cooling, distributes heat throughout the store via ceiling cassettes and tempers air entering the building via a heat exchanger located in the air handing units, designed and built on-site by Ultra’s team of engineers.

In order to cool the live fish, plate heat exchangers, one connected to each pack, chill glycol to just below 0ºC. This is then pumped around a small circuit to internally chill the saltwater via a secondary specialised, purpose built plate heat exchanger. A custom RDM Intuitive TDB controller both monitors and controls the pumps, valves, glycol and saltwater temperatures.

The client’s live fish display was at the forefront of the retail project, it was essential that the store front window did not mist to obscure the view from passing customers. Ultra designed and built a dehumidifier, connected to the central plant with custom control software, using RDM’s free license TDB programmable logic software. Based on the stores current cooling or heating demand dry air is distributed over the window by chilling and reheating, air is then recirculated via a ducted unit mounted discreetly above the ceiling. The system operates only when required by detecting the moisture content deposited on the glass using a resistive sensor built by Ultra exclusively for this application.

Each ceiling cassette features customised controllers, delivering heating or cooling to each area of the shop.  Each cassette can be zoned for optimum comfort and energy control, for example heat is prioritised over the checkouts, whilst cassettes in the chilled food isles have a lower priority.

Selected from the Intuitive TDB range of programmable logic controllers, manufactured by RDM, the 38 controllers are networked to RDM’s DMTouch, a touch screen central monitoring point, located near to the manager’s office.

The system constantly monitors refrigerant pressures, coldroom door use, temperatures, water pressure, and faults, while recording any anomalies and instantly relaying them to on-site staff and by email to SeeWoo’s technical services manager, Henry Pirie, and to Ultra’s support services team.

The DMTouch takes input from the fire alarm to shut down ventilation systems in the event of a fire and from the intruder alarm so that case lighting, heating and cooling can be disabled when the store is closed. It also contains highly customised ‘virtual’ control software to automate heating or cooling demand, valve and defrost control whilst timers, ambient conditions and occupancy data are broadcast throughout the local network enabling smart control of devices without the need for human intervention; or error.