YORK Johnson Controls: Automation of high-rise refrigeration.
YORK Johnson Controls has its own special examples of the implementation of automated control systems for the refrigeration of high-rise buildings.
In accordance with MGSN, refrigeration systems and refrigeration units of high-rise buildings must:
— ensure the specified parameters of the coolant during the billing period, the ability to regulate the cooling capacity and energy efficiency;
— be safe for the life and health of residents and service personnel, as well as for the safety of the building and property;
— be reliable, durable and maintainable.
All these tasks are solved by using modern microprocessor control systems.
The specified parameters of the coolant at any time of the year and during the billing period are achieved by using refrigeration machines with microprocessor control, automatically regulating their productivity depending on the required parameters, as well as by using software control of fans of other types of coolers and implementing additional control circuits in the refrigeration system.
Equipment safety is ensured by using high-quality and reliable equipment installed in special control panels with limited access.
Reliability and durability are achieved by using only high-quality system components with a mean time between failures of at least 10 years, as well as special measures to back up the most important control units. It is also necessary to constantly monitor the operating parameters of the equipment and provide timely warnings about possible malfunctions.
The refrigeration center of a high-rise building is a serious consumer of energy resources, and it is important to use energy-efficient equipment and special energy-saving control algorithms in the control system.
Principles of building automated systems for high-rise buildings
A refrigeration control system is most often one or more controllers that perform local tasks and are connected via a digital interface into a network with the ability to exchange data with central control stations or a dispatching system.
Building refrigeration center control systems designed and supplied by YORK Johnson Controls most often consist of refrigeration machine controllers and a central controller for process equipment control (fans, pumps, valves, dampers, etc.). By using unified approaches to data transmission, the central controller and refrigeration machine control systems constantly exchange information.
Therefore, special energy-saving control algorithms are implemented, when the maximum estimated cold load is distributed among several refrigeration machines operating in parallel during peak load hours, and individual refrigeration machines are switched off when the cold load in the building decreases. The central controller ensures automatic maintenance of the coolant parameters in circuits using other types of coolers (dry coolers, cooling towers, etc.) in winter, and also performs shock-free switching of seasonally operating equipment without the participation of service personnel.
Also, all systems provide for the redundancy of the most important components (for example, pumps and fans) and automatic input of the reserve with the issuance of an emergency message. A feature of high-rise buildings is a large number of separate zones with local coolers, so a very important task of the refrigeration system is to maintain the required hydraulic modes to prevent imbalance of the system.
To achieve this, YORK Johnson Controls automation systems use frequency control of refrigeration pump drives and special control algorithms with monitoring of hydraulic parameters in individual zones.
The basis of any high-rise building management system is a dispatching system that combines control and management of the entire complex of complex engineering equipment distributed throughout the building. Therefore, a modern automated refrigeration system must be able to be easily and reliably integrated into any dispatching control system.
All YORK Johnson Controls automation equipment supports the BACnet protocol, which allows installing automated refrigeration systems at any dispatching stations.
Examples of implementation of refrigeration control systems for high-rise buildings.
YORK Johnson Controls has extensive experience in implementing high-rise building automation projects. These include the Central Bank of the Russian Federation Computer Center, the high-rise building complex on Novy Arbat, the Capital Group office building, the Timiryazevsky multifunctional complex, and a number of other high-rise buildings.
As an example, let us consider the features of constructing an automated refrigeration system for a high-rise building complex on Novy Arbat, which supplies a coolant with strictly specified parameters to a high-rise complex, as well as cultural and commercial buildings on Novy Arbat Street (Fig. 1).
The refrigeration system consists of two independent circuits with different parameters of the coolant and includes the following systems:
1. Refrigeration machines. Two of them operate on one circuit and one, depending on a number of parameters, automatically switches from one circuit to another.
2. The system for supplying the coolant to consumers, including a unit for automatically maintaining design pressure drops (Fig. 3).
3. The circulating water supply system, providing cooling and supply of circulating water to the condensers of refrigeration machines.
4. Cooling towers.
5. The automated make-up system with a choice of water sources — tap or artesian.
All control equipment is mounted in the basement, in close proximity to the automated engineering systems, and consists of control cabinets connected by an interface cable (Fig. 4). Also connected to the data transmission network are the refrigeration machine controllers and the dispatch control station based on the YORK Facility Manager software (Fig. 2).
The automation system design provided for several interesting solutions, including: a) the ability to seamlessly switch the refrigeration machine from one refrigeration circuit to another with gradual pressure equalization;
b) automatic maintenance of pressure drops in the circuits to protect the equipment; c) the possibility of using existing artesian wells, etc. as a water source.
Over two years, the system has proven itself to be reliable, easy to operate and maintain, and has made it possible to continuously supply coolant to consumers while minimizing energy and material flow costs.