Hybrid Tandem Compressor Control for Low-Load HVAC Cycling
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Solution Overview
Problem
HVAC systems with variable-speed compressors face inefficiencies due to the need for repeated on/off cycles during low cooling or heating loads, as they cannot maintain desired environmental conditions, leading to increased energy consumption.
Innovation Solution
A compressor system comprising a variable-speed compressor and a fixed-speed compressor, controlled by a unit that measures environmental conditions and directs their operation based on determined HVAC loads, allowing for optimized capacity matching and reduced cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a variable-speed compressor is used to improve HVAC system efficiency, then energy consumption is reduced during high load conditions, but the system cannot maintain desired environmental conditions during low load conditions, leading to repeated on/off cycling
Solution Approach 1:
The patent combines a variable-speed compressor and a fixed-speed compressor into a single HVAC system. The variable-speed compressor handles high load conditions efficiently, while the fixed-speed compressor provides reliable capacity during low load conditions, eliminating the need for repeated on/off cycling and maintaining environmental conditions reliably.
Solution Approach 2:
The system dynamically switches between different compressor configurations based on load conditions. The control unit monitors HVAC load and adjusts which compressor operates and at what speed, optimizing performance across varying conditions rather than relying on a single compressor type.
2Adaptability or versatility
If a variable-speed compressor operates at minimum capacity, then it can handle small HVAC loads, but it requires repeated on/off cycling which introduces further inefficiencies
Solution Approach 1:
By merging a variable-speed compressor with a fixed-speed compressor, the system can handle small HVAC loads using the fixed-speed compressor operating at its optimal capacity rather than forcing the variable-speed compressor to operate at inefficient minimum speeds or cycle on/off repeatedly.
Solution Approach 2:
The system changes operational parameters by switching between different compressor types based on load magnitude. For small loads, the fixed-speed compressor is activated with the variable-speed compressor shut off, changing the operational state from variable-speed minimum capacity to fixed-speed optimal capacity, thereby eliminating cycling inefficiencies.
3Device complexity
If a single compressor is used in the HVAC system, then device complexity is reduced, but the system cannot optimize capacity matching for varying HVAC loads
Solution Approach 1:
The system dynamically selects and adjusts compressor operation based on real-time HVAC load conditions. The control unit continuously monitors load and adjusts which compressor operates and at what speed, enabling optimal capacity matching across the full range of load conditions while maintaining manageable system complexity through automated control.
Data Source
AI summary
A compressor system includes a variable-speed compressor and a fixed-speed compressor. A control unit is operatively coupled to the variable-speed compressor and is operatively coupled to the fixed-speed compressor. A sensor is operatively coupled to the control unit and disposed in an enclosed space. The sensor measures at least one of a temperature and a relative humidity of the enclosed space and determines an HVAC load of the enclosed space. Responsive to a determination of the HVAC load, the control unit directs operation of the variable-speed compressor and the fixed-speed compressor.