Daikin provided Basildon University Hospital in London with two EWAH-TZ air-cooled screw compressor chillers equipped with Variable Frequency Drive (VFD) technology and using HFO refrigerant. These chillers were installed to enhance temperature and humidity control, boosting cooling capacity while simultaneously lowering operating costs.
Products
2 x EWAH-TZ
Total cooling capacity: 1708.4 kW
Project challenges & Daikin solutions
New government guidelines have placed greater emphasis on hospital ventilation and cooling systems. Essex Cardiothoracic Centre (CTC) at Basildon University Hospital is now future proofed against climate change for the near future. As a result, Daikin units were chosen to meet these new requirements. As a result of global warming, temperatures have risen, posing a challenge to the old units located on the roof of the CTC, close to the road and facing the bridge. The inability of these units to adequately control temperature and humidity, coupled with insufficient cooling capacity to meet demand, necessitated an improvement in cooling capacity. As a result, the CTC, which is separate from the main hospital complex but connected by an enclosed bridge, needed to be upgraded to ensure it could effectively meet current demands.
Another key objective was to minimise installation time by speeding up the process, especially as removing the old chillers required using a crane and the service road was closed to traffic. The two new Daikin VFD chillers were efficiently positioned on the roof, allowing the CTC to reopen on time on Monday morning. Daikin's TZ chiller range represents meticulous design, tailored to improve chiller operation and performance for both comfort and process applications in a wide range of climatic conditions.
A key priority for the customer was to reduce operating costs and improve the installations' profitability, efficiency, and cost-effective management. The chillers feature a high-efficiency single-screw VFD compressor design, a generous condenser coil surface area to maximise heat transfer and minimise discharge pressure, high-capacity condenser fans and a direct expansion shell and tube evaporator with minimal refrigerant pressure drop. This combination ensures optimum efficiency at both full and part load. The semi-hermetic single-screw compressor with integral VFD, designed and manufactured by Daikin, further underlines the commitment to superior performance and reliability.
This project exemplifies our extensive experience and ongoing commitment to research and development, meticulously tailored to operate with R1234ze(E) refrigerant, which has a Global Warming Potential of 7. The compressor geometry has been completely redesigned to achieve peak efficiency at full load, while the integration of a VFD allows the compressor speed to be modulated seamlessly, resulting in unparalleled part load efficiency. This commitment to innovation ensures optimum performance under a wide range of operating conditions, reflecting our relentless pursuit of excellence.
Variable frequency drive technology from Daikin
Part-load efficiency is significant in HVAC systems. It is widely accepted that these systems spend most of their operating hours outside their design parameters. If we examine a typical cooling load profile, we will find that the equipment is operating at part load most of the time. As a result, various HVAC components are operating at off-design conditions, requiring efficient and reliable performance.
This efficiency can be achieved through Variable Frequency Drive (VFD) or Inverter technology, which modulates compressor speed by changing the frequency of the motor power supply, thereby regulating compressor capacity. The cost savings associated with reduced operation are typically linked to the ability of the hydronic system to manage part load demand.
The VFD, an electronic power component, enables the compressor to precisely match the varying load requirements of the building by adjusting compressor capacity, providing exceptional part-load efficiency and significant energy-saving opportunities. Daikin's proprietary VFD technology, integrated with its single-screw compressors and Variable Volume Ratio (VVR), further enhances compressor operation under all conditions, resulting in increased efficiency and reduced operating costs.
What sets Daikin's VFD apart is its refrigerant-cooled design, which ensures that its performance is not affected by environmental factors such as ambient temperature, altitude, or air quality, ensuring outstanding reliability.
The benefits of Inverter technology
Most HVAC equipment operates at part load conditions for extended periods. As a result, chiller compressors experience many hours of off-design operation. It is important to prioritise chillers that deliver optimum performance even at part load.
This requirement is met by units equipped with Inverters or Variable Frequency Drives (VFD), which adjust the capacity of the compressor according to demand. Inverter technology continuously regulates the motor speed of the compressor, providing the most efficient method of capacity control. The result is exceptional part-load efficiency, which translates into lower operating costs.
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