Method and system for compressor modulation in non-communicating mode
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Solution Overview
Problem
HVAC systems with single-speed compressors face inefficiencies in dehumidification and energy consumption due to repeated cycling between active and de-activated states, especially in situations with high relative humidity and low sensible cooling loads, as they struggle to maintain thermal comfort and humidity control effectively.
Innovation Solution
The integration of a variable-speed compressor system with a compressor controller and pressure sensor, allowing the HVAC controller to modulate the compressor speed based on environmental conditions, such as outdoor temperature and refrigerant pressure, to optimize run time and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-speed compressor is used in HVAC systems, then the system structure is simple and cost-effective, but the system experiences repeated cycling between active and de-activated states leading to poor dehumidification efficiency and high energy consumption
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a static single-speed compressor to a variable-speed compressor that can dynamically adjust its operating speed. The compressor controller receives signals from the HVAC controller and modulates the compressor speed continuously between 0% and 100% of its maximum capacity, allowing the system to adapt to varying cooling loads and maintain optimal operation without repeated cycling.
Solution Approach 2:
The patent implements parameter changes by modifying the operational parameters of the compressor, specifically its speed parameter. Instead of operating at a fixed speed, the compressor's rotational speed is continuously adjusted based on system conditions such as refrigerant pressure (monitored by the pressure sensor) and cooling demands, enabling efficient operation across different load conditions and eliminating the energy-wasting on/off cycling behavior.
2Power
If a single-speed compressor operates at full capacity, then cooling capacity is maximized, but dehumidification efficiency deteriorates under partial load conditions with high relative humidity
Solution Approach 1:
The variable-speed compressor enables dynamic adjustment of cooling capacity to match actual dehumidification needs. Under partial load conditions with high relative humidity, the compressor operates at reduced speeds (e.g., 30-70% of maximum) rather than cycling on and off at full capacity. This continuous operation at optimized speeds maintains evaporator coil temperatures that favor condensation and dehumidification while avoiding the thermal shocks and inefficiencies associated with repeated full-capacity cycling.
Solution Approach 2:
The patent applies continuity of useful action by eliminating the discontinuous on/off cycling behavior of single-speed compressors. The variable-speed compressor maintains continuous operation, adjusting its speed smoothly to match cooling and dehumidification demands. This continuous operation ensures consistent refrigerant flow and evaporator coil temperatures, which are critical for effective moisture removal from the air, especially during part-load conditions when dehumidification is most challenging.
3Loss of energy
If a variable-speed compressor system is implemented, then energy efficiency and dehumidification improve, but device complexity increases with additional controllers and sensors
Solution Approach 1:
The compressor controller is designed with multi-functionality, serving multiple roles within the HVAC system. It not only controls the variable-speed compressor but also receives and processes signals from the HVAC controller, interfaces with the pressure sensor for refrigerant pressure monitoring, and implements the modulation logic. This consolidation of functions into a single controller reduces the need for separate dedicated control devices, thereby mitigating the increase in system complexity while achieving variable-speed operation.
Solution Approach 2:
The pressure sensor acts as an intermediary element that provides critical feedback information about refrigerant pressure to the compressor controller. This single sensor enables the controller to make informed decisions about compressor speed modulation without requiring a complex array of sensors. The pressure information serves as a key input for determining optimal operating conditions, allowing the system to achieve efficient dehumidification and energy savings through a relatively simple sensing approach.
Data Source
AI summary
An HVAC system includes a pressure sensor is disposed in a suction line between a compressor and an indoor heat-exchange coil. The pressure sensor is electrically coupled to a compressor controller. An HVAC controller is electrically coupled to the compressor controller. The HVAC controller is configured to transmit a signal to the compressor controller to activate and de-activate the compressor. The compressor controller is configured to receive a signal from the HVAC controller to activate the compressor, determine a start speed of the compressor, monitor a run time of the compressor, and modulate a speed of the compressor.