Central Air Conditioning Solution with Hitachi Chiller System Using Screw Compressors

Central air conditioning (HVAC) systems play a core role in large-scale projects such as office buildings, manufacturing plants, hospitals, and high-end shopping malls. In these projects, optimizing operating costs is always a top priority for investors, as HVAC systems often account for 30% to 40% of the total energy consumption of the entire building. Even a small improvement in efficiency can yield enormous economic benefits. Facing this challenge, Hitachi has firmly established its leading position by continuously innovating technology and providing a perfect solution for investors. Hitachi Chiller systems, utilizing the latest generation screw compressors, are the optimal solution, perfectly balancing powerful cooling performance, mechanical durability, and superior energy savings. This article will provide you with a comprehensive overview, from core technology and classification of prominent product lines to the advantages and technical considerations when installing Hitachi screw chiller systems.

The core technology of Hitachi chiller systems utilizes screw compressors

Hitachi has supplied between 170,000 and 200,000 twin-screw compressor units globally, effectively serving air conditioning needs in many countries with its new generation G-type compressors featuring groundbreaking technical improvements:

• The semi-enclosed design of the G-type compressor integrates the electric motor directly inside the housing, completely eliminating the need for external mechanical couplings. This design completely eliminates the risk of refrigerant leakage into the environment, ensuring a tight and safe operating system. In addition to high efficiency, optimized cooling cycle, greater accuracy, and higher stability, the new water-cooled chiller uses a semi-enclosed G-type twin-turbine compressor with auxiliary functions such as heat pumping, cooling, and total heat recovery.
• The rotor features a new design with screw pairs (rotors) developed and machined using advanced 3D grinding technology for extremely high precision. This design minimizes internal gas leakage during compression, reduces friction to the maximum extent, and optimizes the lubricating oil film for sealing.
  The intelligent motor cooling mechanism uses the integrated motor itself as the cooling medium for the refrigerant flow, ensuring the motor windings always operate within the ideal temperature range, minimizing winding burnout and significantly extending equipment lifespan.
• Differential pressure lubrication technology allows the compressor's lubrication system to operate entirely based on the natural pressure difference between the high-pressure and low-pressure sides without the need for a mechanical oil pump (oil pump-less). This improvement eliminates complex moving parts, reduces the risk of failure, and simplifies maintenance procedures.
• The cyclone oil separator is a proprietary centrifugal technology optimally designed through in-depth computer simulations.

What are the different types of Hitachi chiller screw systems?

To flexibly meet various architectural requirements and operating conditions, Hitachi chiller systems are divided into the following flagship product lines:

Hitachi Chiller Screw System Air-cooled - AZ(P)Y1 Series

The AZ(P)Y1 Series uses R134a refrigerant which is environmentally friendly and does not destroy the ozone layer. This is the only line among the four lines that uses air cooling via an axial fan mounted above the condenser, using a G-type fixed-speed screw compressor and shell-and-tube evaporator. Equipped with an innovative beam tube evaporator, including high-performance dry or flooded evaporation depending on the model, providing extremely stable heat exchange. With a flexible power range from 158kW to 1602kW, equivalent to the nominal power range of 45 - 456 RT. The outstanding performance of this product line is the flexible modular connection ability, up to 8 devices of the same model can be connected in parallel through the H-LINK port, pushing the total system capacity up to 1464 RT. Thanks to this intelligent control mechanism, modules can automatically run redundantly with each other. If one module has an unexpected problem or needs to be stopped for maintenance, the remaining modules will automatically adjust capacity to handle the load, ensuring the building never has a cooling interruption. Due to air cooling, the system does not need a cooling tower or cooling water pump, and Hitachi air conditioners help save installation space and make maintenance easier.

Hitachi Chiller System Variable Speed ​​Water-Cooled - WVY Series

The WVY series is characterized by its combination of a flooded evaporator design using advanced heat exchanger tubes and an integrated VFD (Variable Frequency Drive) controller. Therefore, it is the most advanced and energy-efficient series for controlling compressor speed with extremely low soft-start operation, preventing voltage drops in the power grid. Its superior efficiency is achieved with impressive energy efficiency ratings, reaching an EER of up to 5.9 and an IPLV (Intelligent Power Supply Voltage) of up to 9.93 under no-load conditions, far exceeding stringent industry standards. Furthermore, thanks to VFD technology that adjusts frequency according to actual load, the system saves 20% to 30% of annual energy consumption compared to traditional variable-speed chillers. With these savings, the initial investment payback period is typically under two years under most real-world operating conditions. Furthermore, the inverter enables Hitachi Chiller to perform soft start, controlling the starting current to prevent it from exceeding the rated current, thereby eliminating voltage drops and protecting the building's electrical grid. In addition, the power factor is consistently maintained at a very high level of approximately 0.95 across all load ranges, helping investors avoid reactive power penalties from the electricity company.

Hitachi Chiller System Fixed Speed ​​Water-cooled - WZPY & WZY Series

• The WZPY High Efficiency series is a high-performance variable speed chiller series utilizing a flooded evaporator design. Its unique technological feature is the inclusion of a refrigerant distributor at both the inlet and outlet, optimizing the circulation cycle and significantly improving heat exchange efficiency. The WZPY series has a wide power range from 189kW to 1815kW, equivalent to 53 - 516 RT.

• The WZY series offers a highly flexible product range for customers to choose from: Dry Type (for small capacity ranges from 100 - 125 RT): Provides excellent natural oil return without the need for complex oil return pumps or filters, saving on maintenance costs. Flooded Type (for large capacity ranges from 155 - 520 RT): Utilizes advanced heat exchange tubes to deliver extremely high cooling efficiency for large projects.

The outstanding advantages of Hitachi chiller screw systems

Hệ thống Chiller trục vít Hitachi được ưu tiên lựa chọn của giới kiến trúc sư và kỹ sư cơ điện nhờ sở hữu những ưu thế:

• Tiết kiệm năng lượng nhờ điều khiển vô cấp: Máy nén trục vít Hitachi ứng dụng công nghệ điều khiển công suất vô cấp trong dải rộng từ 15% - 100% (hoặc 25% - 100% tùy dòng máy) nhờ sự phối hợp nhịp nhàng giữa van trượt tự động và bộ biến tần. Hệ thống sẽ tự động tăng/giảm công suất chính xác theo nhu cầu tải thực tế của công trình thay vì điều chỉnh theo từng bậc cố định, tránh lãng phí điện năng.
• Thân thiện với môi trường (Eco-friendly) khi sử dụng hoàn toàn môi chất lạnh HFC134a có chỉ số ODP = 0 (Ozone Depletion Potential), hoàn toàn không gây tổn hại đến tầng ozone của trái đất. Toàn bộ các dòng sản phẩm Chiller trục vít của Hitachi đều tuân thủ nghiêm ngặt chỉ thị môi trường RoHS, giới hạn nghiêm ngặt sự xuất hiện của các chất độc hại (như chì, thủy ngân, cadmium...) nhằm đảm bảo an toàn tuyệt đối cho sức khỏe con người và thuận tiện cho việc tái chế thiết bị sau này.
• Độ ồn và độ rung cực thấp: Máy nén trục vít được thiết kế theo cấu trúc vỏ kép (Double-Casing Design). Lớp vỏ kép đóng vai trò như một bức tường cách âm tự nhiên, triệt tiêu tiếng ồn động học và giảm thiểu rung động cơ khí phát ra môi trường xung quanh trong quá trình nén khí.
• Hệ thống điều khiển thông minh (Advanced Intelligent Control): Trung tâm điều khiển là màn hình cảm ứng LCD kích thước lớn hiển thị trực quan. Giao diện thân thiện giúp kỹ sư vận hành dễ dàng kiểm tra toàn bộ các thông số kỹ thuật (nhiệt độ áp suất, trạng thái dòng chảy...) chỉ bằng một cái nhìn. Bộ nhớ tích hợp tính năng lưu trữ nhật ký cảnh báo thông minh, cho phép truy xuất và xem lại chi tiết 10 sự cố gần nhất. Điều này hỗ trợ các kỹ sư bảo trì chẩn đoán chính xác nguyên nhân lỗi và xử lý hệ thống một cách nhanh chóng. Hệ thống tích hợp hàng loạt cảm biến bảo vệ an toàn cao cấp bao gồm: bảo vệ quá dòng động cơ, bảo vệ quá nhiệt khí xả, bộ công tắc dòng chảy chống đóng băng dàn lạnh, van an toàn kép áp suất cao đảm bảo máy luôn vận hành trong giới hạn an toàn.

Hitachi screw chiller systems are the preferred choice of architects and mechanical and electrical engineers due to their advantages:

• Energy saving thanks to stepless control: Hitachi screw compressors utilize stepless power control technology within a wide range of 15% - 100% (or 25% - 100% depending on the model) thanks to the smooth coordination between automatic slide valves and frequency converters. The system will automatically increase/decrease power precisely according to the actual load needs of the building instead of adjusting in fixed steps, avoiding energy waste.
• Environmentally friendly (Eco-friendly) as it uses only HFC134a refrigerant with an ODP = 0 (Ozone Depletion Potential), causing no harm to the Earth's ozone layer. All Hitachi screw chiller product lines strictly comply with the RoHS environmental directive, severely limiting the presence of hazardous substances (such as lead, mercury, cadmium, etc.) to ensure absolute safety for human health and facilitate future equipment recycling.
• Extremely low noise and vibration: The screw compressor is designed with a double-casing structure. The double casing acts as a natural soundproof wall, suppressing dynamic noise and minimizing mechanical vibrations emitted into the surrounding environment during air compression.
• Advanced Intelligent Control System: The control center is a large, intuitive LCD touchscreen. The user-friendly interface allows operating engineers to easily check all technical parameters (temperature, pressure, flow status, etc.) at a glance. The integrated memory features intelligent alarm log storage, allowing for detailed retrieval and review of the 10 most recent incidents. This assists maintenance engineers in accurately diagnosing the cause of faults and quickly resolving system issues. The system incorporates a range of advanced safety sensors, including: motor overcurrent protection, exhaust gas overheat protection, a flow switch to prevent condensation on the evaporator, and dual high-pressure safety valves to ensure the unit always operates within safe limits.

Practical applications and considerations when installing Hitachi chiller screw systems

Applications in daily life and production

Thanks to its wide power range and absolute reliability, Hitachi chiller screw systems perfectly meet the needs of two major application areas: Comfort air conditioning, providing a cool and pleasant environment for public and quiet working spaces such as high-end office buildings, shopping malls, hotel and resort chains, hospitals, and schools. In industrial refrigeration, they help cool production lines in factories or provide strict temperature control for data centers where the system must operate continuously 24/7 without interruption.

Important notes when constructing and installing Hitachi Chillers

In order for the equipment to operate durably and without unfortunate technical problems, the construction unit is required to strictly follow the instructions from manufacturer Hitachi:

• Tilt angle when transporting: When moving the Chiller by rolling or pushing roller methods, the tilt angle of the machine body compared to the horizontal plane must absolutely not exceed 15 degrees. If this angle is exceeded, the machine's center of gravity is deflected, which can lead to the risk of the device tipping over.
• Hoisting angle: When using a crane to lift equipment into position, the angle created by the sling angle must be at least 60 degrees or more compared to the horizontal. At the same time, it is mandatory to insert soft cushioning materials (tarpaulin, rubber sheet...) between the cable and the machine body to avoid scratches on the shell or distortion of the chiller's mechanical structure.
• Maintenance space: The installation site must be calculated to leave space around the machine according to recommended standards to serve periodic inspection and operation. The front of the device (where the display screen and electrical control cabinet are located) must have a clear distance of about 1200mm. The remaining sides and back of the machine must ensure a minimum distance of about 600mm.

The Hitachi screw chiller system is the crystallization of Japanese precision mechanical manufacturing technology combined with modern intelligent control solutions. Not only does it bring powerful cooling performance and durable operation thanks to the exclusive G-type compressor at its heart, Hitachi Chiller also brings enormous economic benefits to investors thanks to the ability to significantly reduce monthly electricity costs and minimal maintenance costs.

The choice of which product line to use, from the modular AZ(P)Y1 air-cooled series, the ultra-energy-efficient WVY inverter series, to the high-efficiency WZPY/WZY variable speed series, will directly depend on the building's architectural structure, the total initial investment, and the project's long-term energy saving goals. A central air conditioning system is a strategic long-term investment. To ensure accurate cooling load calculations, U.P Tech is ready to assist customers in selecting the right model configuration and optimizing costs. Contact U.P Tech – the authorized Hitachi air conditioner distributor in Vietnam – today to have our professional engineers survey your project, provide in-depth technical advice, and receive the best price quote for your project!

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