Ventilator Total Heat Exchanger Control to Suppress Ice Formation
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Solution Overview
Problem
Conventional ventilators do not effectively manage ice formation in total heat exchangers, leading to inefficiencies and increased energy consumption due to fixed threshold values for outdoor temperature and moisture levels, resulting in improper operation of air supply fans and increased ice formation.
Innovation Solution
A ventilator with a control unit that determines air supply fan operation based on estimated ice formation volume using a total heat exchanger model, incorporating sensors for indoor and outdoor temperature and humidity, and a heat exchanger design with moisture-permeable and corrugated boards to optimize heat and moisture exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed threshold values for outdoor temperature and moisture index are used to control air supply fan operation, then the control system is simple to implement, but ice formation in the total heat exchanger increases due to inability to adapt to varying conditions
Solution Approach 1:
The patent implements dynamic control of the air supply fan by continuously monitoring outdoor temperature and humidity conditions, and adjusting the fan's on/off timing accordingly. This dynamic approach replaces fixed threshold control with adaptive control that responds to real-time environmental changes, thereby suppressing ice formation while maintaining reasonable system complexity
Solution Approach 2:
The control system uses feedback from outdoor temperature and humidity sensors to determine when to operate or stop the air supply fan. By incorporating feedback mechanisms that monitor environmental conditions and adjust fan operation accordingly, the system can adapt to varying conditions and prevent ice formation without requiring overly complex device architecture
2Object-generated harmful factors
If the air supply fan stops for extended periods to melt ice, then ice formation is suppressed, but ventilation efficiency and energy consumption deteriorate
Solution Approach 1:
The patent applies partial action by stopping the air supply fan only for the specific duration needed to melt accumulated ice, rather than implementing prolonged stoppages. This allows the system to suppress ice formation effectively while minimizing the impact on ventilation efficiency and energy consumption by resuming normal operation as soon as ice is melted
Solution Approach 2:
The control system implements periodic monitoring of outdoor conditions and periodic adjustment of fan operation. By using periodic action to determine when ice melting is needed and when normal ventilation can resume, the system balances ice suppression with maintained ventilation efficiency, avoiding both continuous operation and excessive stoppages
3Device complexity
If fixed stoppage durations are used for the air supply fan, then control is simple, but the fan may operate before ice melts completely or stop even after ice melts, leading to increased energy consumption
Solution Approach 1:
The patent employs feedback control by continuously monitoring outdoor temperature and humidity conditions to determine the precise timing for fan operation and stoppage. This feedback mechanism ensures the fan operates only when necessary and stops when ice has melted, eliminating wasted energy from premature or extended stoppages while keeping the control mechanism relatively simple
Solution Approach 2:
The control system uses self-service by automatically adjusting fan operation based on real-time environmental conditions without requiring complex external control. The system monitors its own operational needs through temperature and humidity sensing and autonomously determines optimal fan timing, reducing energy waste while maintaining simple control architecture
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
The solution effectively suppresses ice formation in the total heat exchanger, reducing energy consumption and improving ventilation efficiency by dynamically adjusting fan operation based on real-time conditions.
Implementation Method 1
a total heat exchanger which is made with partition boards being moisture-permeable flat parts and with spacer boards being corrugated parts, the partition boards and the spacer boards being alternately stacked, the total heat exchanger exchanging heat between the outdoor air and the indoor air
Implementation Method 2
the total heat exchanger exchanging heat between the outdoor air flowing through a supply passage and the indoor air flowing through an exhaust passage
Implementation Method 3
partition boards being moisture-permeable flat parts
Data Source
AI summary
A ventilator (1) includes: an air supply fan (2) to supply outdoor air to a room; an air exhaust fan (3) to exhaust indoor air, out of the room; and a total heat exchanger (4) which is made with partition boards (41) being moisture-permeable flat parts and with spacer boards (42) being corrugated parts, the partition boards and the spacer boards being alternately stacked, the total heat exchanger exchanging heat between the outdoor air and the indoor air; and thereby suppresses ice formation. The ventilator (1) includes: an indoor temperature sensor (7); an indoor humidity sensor (8); an outdoor temperature sensor (6); and a control unit (5) to control operation of the air supply fan (2) and the air exhaust fan (3) on a basis of at least one state quantity estimated by substituting the indoor air temperature, the indoor air humidity, and the outdoor air temperature in a total heat exchanger model formula (51a) representing characteristics of the total heat exchanger (4).