HVAC Blower Control for Compressor-Off Dehumidification
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Solution Overview
Problem
Existing air processing systems face inefficiencies in dehumidification due to electromechanical humidity monitors that are inefficient and lack precise control, leading to higher energy costs and inadequate comfort levels.
Innovation Solution
A method that compares actual space humidity to the desired level after the compressor is shut off, allowing the blower to continue running if humidity is near or below the desired level, and forcing it off for a period if humidity is higher, optimizing dehumidification by adjusting blower operation based on humidity differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the blower runs continuously at high speed to maintain air circulation, then air movement is maximized, but dehumidification effectiveness decreases due to rapid air passage through the coil
Solution Approach 1:
The blower speed is dynamically adjusted based on operational phase: high speed during compressor operation for air circulation, and low speed during compressor OFF cycles for enhanced dehumidification. This dynamic speed adjustment resolves the contradiction by optimizing air movement speed for different operational requirements.
Solution Approach 2:
The system employs periodic blower operation during compressor OFF cycles, running the blower at low speed for specific durations (e.g., 5-15 minutes) to enhance dehumidification without continuous high-speed operation. This periodic action allows the system to achieve precise dehumidification control while maintaining energy efficiency.
2Manufacturing precision
If the blower speed is reduced to enhance dehumidification, then moisture condensation increases on the coil, but re-evaporation of condensed moisture occurs after compressor shutdown
Solution Approach 1:
The blower is operated at low speed during the period immediately following compressor shutdown, before re-evaporation can occur. This preliminary action removes moisture-laden air from the space while the coil is still cold, preventing re-evaporation and eliminating energy loss associated with this phenomenon.
Solution Approach 2:
The system uses a humidity sensor to monitor space humidity levels and provides feedback to the control system. Based on this feedback, the blower operation is adjusted: if humidity exceeds the setpoint, the blower runs at low speed during compressor OFF cycles to enhance dehumidification; if humidity is acceptable, the blower may be curtailed to save energy.
3Manufacturing precision
If electromechanical humidity monitors are used to control blower speed, then dehumidification is enhanced, but temperature control deteriorates and energy costs increase
Solution Approach 1:
The system uses the existing thermostat-controlled compressor operation to provide cooling, and overlays blower control during compressor OFF cycles to handle dehumidification. This self-service approach allows humidity control without requiring additional cooling capacity, thereby maintaining temperature stability while achieving precise humidity control.
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
Enhances dehumidification effectiveness while reducing energy costs by precisely controlling humidity levels and maintaining comfort, even during compressor OFF cycles.
Implementation Method 1
dehumidification in the area of the 'cold' inside compressor coil
Implementation Method 2
Processed air is delivered to the enclosed space by a blower
Data Source
AI summary
The present invention provides a method for enhancing dehumidification of a conditioned space, while optimizing the effectiveness of Indoor Air Quality (IAQ) devices that are present in the HVAC system. After the system compressor is shut off, the actual space humidity is compared to the desired humidity. If the actual humidity is very close to or lower than the desired level the indoor blower (air handler) is allowed to continue running. However, if the actual humidity is greater than the desired level by a specified amount, the blower is forced off for a period of time proportional to the difference between the actual and desired humidity. At the next compressor activation, the blower is allowed to run as normal.