Cooling Tower Control for Chiller Load and Wet-Bulb Conditions
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Solution Overview
Problem
The existing heat-source systems face inefficiencies in managing the number of cooling towers to optimize overall system efficiency, as activating additional cooling towers can increase power consumption, affecting the balance between centrifugal-chiller and cooling-tower fan power usage.
Innovation Solution
A heat-source system with a control unit that determines the optimal number of cooling towers to operate based on outside-air wet-bulb temperature and centrifugal-chiller partial load factor, using a pre-stored relationship to adjust cooling-tower capacity and cooling-water flow rate for maximum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If additional cooling towers are activated to increase cooling capacity, then the cooling water temperature decreases and centrifugal-chiller efficiency improves, but the cooling-tower fan power consumption increases
Solution Approach 1:
The control unit dynamically adjusts the number of operating cooling towers based on changing system parameters including outside-air wet-bulb temperature and centrifugal-chiller partial load factor. This parameter-based adjustment optimizes the balance between cooling water temperature and fan power consumption, resolving the technical contradiction by adapting the cooling tower configuration to current operating conditions rather than maintaining a fixed setup
Solution Approach 2:
The control unit continuously monitors system performance parameters and uses this feedback to determine the optimal number of cooling towers to operate. By measuring the actual operating conditions and adjusting the cooling tower configuration accordingly, the system achieves optimal efficiency while minimizing the power consumption trade-off between chillers and cooling tower fans
2Loss of energy
If the number of cooling towers is increased to improve heat exchange efficiency, then the overall heat-source system efficiency may improve, but the system complexity and control difficulty increase
Solution Approach 1:
The cooling tower system is divided into multiple independently controllable units, allowing the control unit to selectively activate or deactivate specific towers based on current load requirements. This segmentation enables flexible configuration adjustment without requiring complete system redesign, managing complexity while maintaining optimization capability
Solution Approach 2:
The control unit automatically determines the optimal cooling tower configuration based on pre-stored performance data and current operating conditions, eliminating the need for manual intervention or complex real-time calculations. The system self-adjusts to maintain optimal efficiency, reducing control complexity while achieving energy optimization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for simple and efficient operation by optimizing cooling-tower capacity and flow rates, enhancing the overall heat-source system's efficiency by reducing power consumption and improving COP (Coefficient of Performance).
Implementation Method 1
a cooling tower that cools the cooling water guided from the condenser by the cooling-water pump by bringing the cooling water into contact with the outside air to perform heat exchange
Implementation Method 2
a condenser that condenses the refrigerant gas compressed by the centrifugal-compressor into liquid
Implementation Method 3
an evaporator that evaporates the refrigerant expanded by the expansion valve
Data Source
AI summary
A heat-source system includes centrifugal-chillers, cooling-water pumps, cooling towers, cooling-tower fans, chilled-water pumps, and a control unit for controlling them. A plurality of the cooling towers are provided so as to have a cooling-tower capacity corresponding to the total capacity of the rated capacities of the respective centrifugal-chillers, the cooling towers being commonly connected to the plurality of centrifugal-chillers. The control unit preliminarily prepares an optimum cooling-tower capacity relationship representing the cooling-tower capacity with which the heat-source system efficiency, taking into consideration the centrifugal-chillers, the cooling-water pump, the cooling towers, the cooling-tower fan, and the chilled-water pump, is higher, in relation to the outside-air wet-bulb temperature and the centrifugal-chiller partial load factor. The control unit determines the number of cooling towers to be operated by referring to the optimum cooling-tower capacity relationship, on the basis of the outside-air wet-bulb temperature and the partial load factor of the centrifugal-chillers during operation.