Series Chiller Control Using Variable Intermediate Temperature
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Solution Overview
Problem
Conventional heat source systems with fixed intermediate temperatures are inefficient when heat load demand fluctuates, leading to suboptimal operation of upstream and downstream heat source devices, resulting in higher energy consumption and costs.
Innovation Solution
A heat source system with a control unit that variably sets the intermediate temperature between upstream and downstream heat source devices, allowing each device to operate based on the temperature difference from the intermediate temperature, thereby adjusting their load factors and reducing energy consumption and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intermediate temperature is fixed at a rated value, then the downstream heat source device can operate at 100% load factor, but the upstream heat source device operates at low load factor resulting in high energy consumption
Solution Approach 1:
The patent applies dynamics by making the intermediate temperature variable rather than fixed. The control unit dynamically adjusts the intermediate temperature based on the return temperature and heat load conditions, allowing both upstream and downstream heat source devices to operate at optimal load factors. This resolves the contradiction by enabling the system to adapt to changing conditions while maintaining stable operation.
Solution Approach 2:
The patent changes the parameter of intermediate temperature from a fixed rated value to a variable parameter that is adjusted based on operating conditions. By changing this parameter dynamically, the system can optimize the load factors of both heat source devices and reduce overall energy consumption while maintaining reliable operation.
2Device complexity
If the intermediate temperature is fixed, then the system structure is simple, but the upstream heat source device cannot operate efficiently when heat load demand decreases
Solution Approach 1:
The control system transitions from a static fixed-temperature approach to a dynamic variable-temperature approach. The control unit continuously adjusts the intermediate temperature based on return temperature and load conditions, enabling efficient operation across varying heat demand while adding only minimal control complexity.
Solution Approach 2:
The patent implements feedback control where the control unit monitors the return temperature and heat load conditions, then adjusts the intermediate temperature accordingly. This feedback mechanism enables the upstream heat source device to operate efficiently under varying conditions without requiring complex manual intervention or system redesign.
3Loss of energy
If the intermediate temperature is variably set, then the load factor of each heat source device can be optimized, but the control system becomes more complex
Solution Approach 1:
The patent optimizes energy loss by dynamically changing the intermediate temperature parameter based on operating conditions. The control unit calculates the optimal intermediate temperature that maximizes the load factors of both heat source devices, thereby minimizing energy loss. This parameter change approach achieves energy optimization with relatively simple control logic.
Solution Approach 2:
The control system performs self-service by automatically adjusting the intermediate temperature based on monitored conditions without requiring external intervention. The control unit independently optimizes the operation of both heat source devices by varying the intermediate temperature, reducing energy loss while maintaining simple autonomous control.
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 enables efficient operation by optimizing the load factor of each heat source device, reducing energy consumption and operation costs, and improving overall system performance.
Implementation Method 1
an upstream heat source device that changes the temperature of the heat medium from the return temperature to an intermediate temperature
Implementation Method 2
a downstream heat source device that changes the temperature of the heat medium that has been changed to the intermediate temperature by the upstream heat source device, to the supply temperature
Data Source
AI summary
Provided is a heat source system that includes two heat source devices connected in series to a heat medium and can be efficiently operated. A heat source system (1) reduces the temperature of chilled water that is guided from a cooling load and has a predetermined return temperature Tr, to a predetermined supply temperature Ts, and supplies the chilled water to the cooling load. The heat source system (1) includes: a second centrifugal chiller (TR2) that reduces the temperature of the chilled water from the return temperature Tr to an intermediate temperature T2; a first centrifugal chiller (TR1) that reduces the temperature of the chilled water that has been reduced to the intermediate temperature T2 by the second centrifugal chiller (TR2), to the supply temperature Ts; and a control unit (9) that variably sets the intermediate temperature T2.