Cascade Heat Pump Control for Chilled and High-Temperature Water
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Solution Overview
Problem
Conventional heat source systems for semiconductor fabrication facilities are inefficient in energy usage, particularly when obtaining high-temperature water, as they rely on boilers that achieve less than 1 efficiency, compared to heat pumps which can achieve a Coefficient of Performance (COP) of 3 or more, leading to increased energy consumption and CO2 emissions.
Innovation Solution
A heat source system incorporating a chilled-water main control heat pump and a hot-water main control heat pump, where the lower-stage condenser's exhaust heat is used to heat medium-temperature water, which is then used to evaporate refrigerant for high-temperature water production, with the cooling water temperature set to ensure efficient operation of both systems, minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a boiler is used to obtain high-temperature water, then high-temperature water can be supplied, but energy efficiency deteriorates (efficiency becomes 1 or less)
Solution Approach 1:
The invention changes the temperature parameter strategy by setting a lower temperature limit for cooling water based on the required high-temperature water output. This ensures the heat pump system operates in an efficient temperature range, maintaining high COP while achieving the required high-temperature water supply without using a boiler
Solution Approach 2:
The heat pump system is designed to perform multiple functions: it supplies chilled water through the evaporator, recovers heat through the condenser to produce medium-temperature water, and further processes this to produce high-temperature water. This multi-functionality replaces the need for separate boiler and chiller systems, achieving high energy efficiency while meeting all thermal requirements
2Use of energy by moving object
If cooling water temperature is lowered to improve chilled-water heat pump efficiency, then chilled-water system efficiency improves, but medium-temperature water temperature may become insufficient for high-temperature water production
Solution Approach 1:
The control device continuously monitors the required high-temperature water temperature and adjusts the cooling water temperature lower limit accordingly. This feedback mechanism ensures that the cooling water temperature is maintained at an optimal level that satisfies both the chilled-water heat pump efficiency requirements and the high-temperature water production requirements
Solution Approach 2:
The system dynamically adjusts the cooling water temperature lower limit based on the required high-temperature water temperature. When high-temperature water requirements change, the control device modifies the cooling water temperature setpoint to maintain optimal operation of both the chilled-water and hot-water heat pump systems
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 configuration allows for the efficient production of both chilled and high-temperature water, optimizing energy efficiency and reducing CO2 emissions by setting cooling water temperatures based on the required high-temperature water temperature, ensuring the medium-temperature water is maintained for efficient hot-water production and the chilled-water system operates at optimal efficiency.
Implementation Method 1
a lower-stage evaporator that cools chilled water by the vaporization heat of refrigerant
Implementation Method 2
a lower-stage condenser that dissipates the condensation heat of the refrigerant into cooling water
Implementation Method 3
a higher-stage evaporator that evaporates the refrigerant with the heat provided from medium-temperature water
Implementation Method 4
a higher-stage condenser that heats high-temperature water with the condensation heat of the refrigerant
Data Source
AI summary
An object is to provide a heat source system capable of realizing energy saving. In a heat source system including: a chilled-water main control heat pump (1) having a lower-stage evaporator (9) that cools chilled water and a lower-stage condenser (7) that dissipates heat into cooling water, and outputting the chilled water cooled in the lower-stage evaporator (9) to an external load; and a hot-water main control heat pump (51) having a higher-stage evaporator (59) to which heat is provided by medium-temperature water that has been heated with the exhaust heat from the lower-stage condenser (7) and a higher-stage condenser (57) that heats high-temperature water, and outputting the high-temperature water heated in the higher-stage condenser (57) to an external load; a lower temperature limit of the cooling water is set on the basis of a set temperature of the high-temperature water.