Peak demand response operation with improved sensible capacity
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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 maintain comfort 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 for improved sensible capacity and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the HVAC system operates at high power consumption to maintain comfortable temperatures, then cooling capacity is improved, but power consumption increases during peak demand response times
Solution Approach 1:
The system dynamically adjusts the ratio of air flow rate to cooling capacity by varying blower speed and compressor tonnage in real-time. During peak demand response times, the system maintains a higher CFM/ton ratio than conventional systems, which allows it to preserve sensible cooling capacity while operating at reduced power consumption levels. This dynamic adaptation resolves the contradiction between maintaining comfortable temperatures and reducing power consumption.
Solution Approach 2:
The system changes the operating parameters of the HVAC equipment, specifically maintaining a higher CFM/ton ratio through coordinated control of blower and compressor speeds. This parameter change enables the system to operate efficiently at lower power consumption while still providing adequate sensible cooling to maintain comfortable temperatures during peak demand response periods.
2Use of energy by moving object
If the compressor speed is decreased to reduce power consumption, then power consumption is reduced, but sensible capacity decreases
Solution Approach 1:
The system dynamically adjusts both compressor speed and blower speed in a coordinated manner to maintain an optimized CFM/ton ratio. When compressor speed is decreased to reduce power consumption, the blower speed is also adjusted to maintain the optimal air flow rate relative to the reduced cooling capacity. This dynamic coordination ensures that sensible capacity is preserved proportionally more than in conventional systems during demand response events.
Solution Approach 2:
The control system manages multiple functions simultaneously: it reduces power consumption to meet demand response requirements while also maintaining sensible cooling capacity to preserve occupant comfort. The coordinated control of blower and compressor achieves both objectives that would normally be contradictory, demonstrating multi-functionality in resolving the technical contradiction.
3Power
If the air flow rate is increased to maintain sensible capacity, then sensible capacity is improved, but power consumption increases
Solution Approach 1:
The system optimizes the CFM/ton ratio parameter by coordinating changes in both air flow rate and cooling capacity. Rather than simply increasing air flow rate to maintain sensible capacity (which would increase power consumption), the system adjusts both parameters together to maintain an optimized ratio. This allows the system to preserve sensible capacity while minimizing the associated power consumption increase during demand response events.
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 enhances cooling efficiency and maintains comfortable temperatures during peak demand response times by increasing sensible capacity, while satisfying power reduction requirements, providing more effective cooling than previous technologies.
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
Implementation Method 3
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 is adjusted to the predefined setpoint temperature. The variable-speed compressor is adjusted to a low-speed setting, thereby operating the HVAC system at a first tonnage of cooling. The rate of the flow of air provided by the blower is adjusted to a first flow rate, such that a ratio of the first flow rate to the first tonnage of cooling is increased to a first predefined value.