Variable-Speed HVAC Demand Response With Sensible Cooling Shift
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Solution Overview
Problem
HVAC systems face challenges in maintaining comfortable temperatures during peak demand response times while reducing power consumption, as existing technologies lack effective methods to increase sensible capacity and improve cooling efficiency under restricted operating conditions.
Innovation Solution
The implementation of a variable-speed compressor and blower system, along with a controller that adjusts compressor speed and air flow rate to increase the sensible heat ratio, and the use of a face-split evaporator to deactivate the bottom evaporator circuit for evaporative cooling, allowing the system to operate at increased sensible capacity while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the HVAC system operates at high capacity to maintain comfortable temperatures, then cooling performance is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the ratio of sensible to latent cooling capacity in real-time based on outdoor conditions and indoor load requirements. The controller modulates the refrigerant flow and air handling to optimize the sensible heat ratio, allowing the system to adapt between high sensible cooling (when needed for comfort) and reduced power consumption (when outdoor conditions permit), thereby resolving the contradiction between cooling performance and energy use.
Solution Approach 2:
The system changes the operating parameters of the HVAC equipment, specifically the sensible heat ratio, to optimize performance. By controlling the refrigerant circulation rate, evaporator temperature, and air flow rate, the system can shift between different cooling modes (high sensible vs. high latent) to match outdoor conditions, thus achieving comfortable temperatures while minimizing power consumption during peak demand periods.
2Use of energy by moving object
If the compressor speed is reduced to lower power consumption, then energy use decreases, but cooling capacity is reduced
Solution Approach 1:
The system changes the operating parameters of the HVAC equipment, specifically the sensible heat ratio, to optimize performance. By controlling the refrigerant circulation rate, evaporator temperature, and air flow rate, the system can shift between different cooling modes (high sensible vs. high latent) to match outdoor conditions, thus achieving comfortable temperatures while minimizing power consumption during peak demand periods.
Solution Approach 2:
The system dynamically adjusts the ratio of sensible to latent cooling capacity in real-time based on outdoor conditions and indoor load requirements. The controller modulates the refrigerant flow and air handling to optimize the sensible heat ratio, allowing the system to adapt between high sensible cooling (when needed for comfort) and reduced power consumption (when outdoor conditions permit), thereby resolving the contradiction between cooling performance and energy use.
3Use of energy by moving object
If the system operates under restricted operating requirements during peak demand, then power consumption is reduced, but ability to maintain comfortable temperatures deteriorates
Solution Approach 1:
The system changes the operating parameters of the HVAC equipment, specifically the sensible heat ratio, to optimize performance. By controlling the refrigerant circulation rate, evaporator temperature, and air flow rate, the system can shift between different cooling modes (high sensible vs. high latent) to match outdoor conditions, thus achieving comfortable temperatures while minimizing power consumption during peak demand periods.
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 solution enhances cooling efficiency and maintains comfortable temperatures during peak demand response times by increasing the sensible capacity of HVAC systems, effectively addressing the limitations of previous technologies in managing peak demand while reducing power consumption.
Implementation Method 1
a variable-speed compressor configured to compress refrigerant flowing through the HVAC system
Implementation Method 2
The top evaporator circuit is configured to transfer heat from a first portion of a flow of air passing across the top evaporator circuit to refrigerant in the top evaporator circuit. The bottom evaporator circuit is configured to transfer heat from a second portion of the flow of air passing across the bottom evaporator circuit to refrigerant in the bottom evaporator circuit.
Implementation Method 3
a blower configured to provide a flow of air through the HVAC system at a controllable flow rate
Implementation Method 4
A first portion of the liquid condensate formed on a surface of the top evaporator circuit is allowed to fall on a surface of the bottom evaporator circuit such that the second portion of the flow of air is evaporatively cooled by the first portion of the liquid condensate.
Data Source
AI summary
An HVAC system includes a variable-speed compressor which compresses refrigerant flowing through the HVAC system, a blower which provides a flow of air through the HVAC system at a controllable flow rate, and a controller communicatively coupled to the variable-speed compressor and the blower. The controller receives a demand request, which includes a command to operate the HVAC system at a predefined setpoint temperature. In response to receiving the demand request, a setpoint temperature associated with the HVAC system can be adjusted to the predefined setpoint temperature. A speed of the variable-speed compressor is decreased to a low-speed setting. Based on the decreased speed of the variable-speed compressor, an air-flow rate can be determined to provide by the blower. The controllable flow rate of the flow of air provided by the blower can be adjusted based on the determined air-flow rate.