Variable speed blower control for HVAC systems
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Solution Overview
Problem
Conventional HVAC systems face inefficiencies due to excess cooling capacity at varying outdoor ambient temperatures, leading to increased energy consumption and complexity, as they rely on multi-stage compressors that require additional hardware and result in a larger physical footprint.
Innovation Solution
The use of a variable speed blower to adjust cooling capacity by dynamically changing fan speed in response to temperature changes, allowing for reduced energy consumption and complexity without the need to turn off compressors, and providing both coarse and fine adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-stage compressors are used to adjust cooling capacity, then cooling capacity can be adjusted, but device complexity and physical footprint increase
Solution Approach 1:
The patent extracts the cooling capacity adjustment function from the compressor and relocates it to the blower system. By using a variable speed blower to control airflow through the evaporator, the system achieves cooling capacity modulation without requiring multiple compressors or complex compressor staging hardware, thereby reducing device complexity while maintaining adaptability
Solution Approach 2:
The blower is given a dual function: it serves both as the air moving component and as the cooling capacity control mechanism. By varying blower speed, the same component performs both airflow delivery and cooling load matching, eliminating the need for separate multi-stage compressor hardware and reducing overall system complexity
2Adaptability or versatility
If multiple compressors are used to adjust cooling capacity, then cooling capacity can be adjusted, but costs increase
Solution Approach 1:
The patent removes the need for multiple compressor units and their associated control hardware by extracting the capacity modulation function and implementing it through variable speed blower control. This eliminates the cost of additional compressors, mounting hardware, electrical controls, and installation infrastructure
Solution Approach 2:
The patent merges the cooling capacity control function into the existing blower system by implementing variable speed control. This consolidation eliminates the need for separate compressor staging hardware and controls, reducing both equipment costs and installation costs while achieving the same cooling capacity adjustment capability
3Loss of energy
If compressors are turned off to reduce excess cooling capacity, then energy consumption is reduced, but cycling increases
Solution Approach 1:
The patent implements dynamic cooling capacity control through variable speed blower adjustment rather than static on/off compressor operation. The blower speed can be continuously modulated to precisely match the cooling load, preventing the large temperature swings and frequent cycling that occur with compressor on/off operation, thereby improving system reliability while reducing energy consumption
Solution Approach 2:
The patent changes the control parameter from discrete compressor on/off states to continuous blower speed variation. By adjusting the blower speed parameter, the system can smoothly modulate cooling capacity to match varying loads without the abrupt transitions that cause compressor cycling, reducing both energy waste and reliability issues
Data Source
AI summary
A temperature control system that includes a sensor, a variable speed blower, and a controller. The controller is configured to receive an air temperature measurement from the sensor and determine a temperature value based on the received air temperature measurement. The controller is further configured to compare the determined temperature value to a first threshold value and a second threshold value and to operate the variable speed blower based on the comparison. The controller is configured to set the variable speed blower to a first fan speed when the temperature value is below the first threshold value and to a second fan speed when the temperature value is above the second threshold value. The controller is further configured to set the variable speed blower to a third fan speed that linearly correlates with temperature when the temperature value is between the first threshold and the second threshold.