Heat-Exchange Ventilation Heater Control at Low Airflow
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Solution Overview
Problem
Existing heat-exchange ventilation devices face issues with excessive temperature increase and frequent heater turning-on/off when operated at smaller air volumes than designed, leading to inefficient heating and potential safety risks.
Innovation Solution
A heat-exchange ventilation device with a control unit that regulates the air supply fan intensity and heater operation based on temperature measurements, prohibiting heater activation at lower fan intensities than set, and incorporating modes to prioritize air volume or heater operation for optimal temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a heater with capacity corresponding to maximum air volume is used, then the heater can meet the heating demand at maximum air volume, but the heater temperature excessively increases when operated at minimum air volume
Solution Approach 1:
The patent applies dynamics by making the air supply fan speed variable rather than fixed. The control unit adjusts the fan speed to match the heater's operating capacity, ensuring that the air volume through the heater remains within a safe temperature range regardless of whether the heater operates at high or low capacity. This dynamic adjustment of airflow prevents overheating while maintaining heating effectiveness.
Solution Approach 2:
The patent changes the operating parameters of the system by introducing variable fan speed control. Instead of operating the fan at a fixed speed, the control unit dynamically adjusts the fan speed parameter based on heater capacity and operating conditions. This parameter change ensures optimal matching between heater capacity and airflow, preventing excessive temperature rise.
2Device complexity
If the heater is controlled only by turning on or off energization, then the control is simplified and cost is suppressed, but frequent turning-on and turning-off affects relay life
Solution Approach 1:
The patent introduces dynamic control of the air supply fan speed while maintaining simple on/off control of the heater. By dynamically adjusting fan speed, the system can modulate heating output without频繁ly switching the heater on and off, thereby protecting relay life while keeping control complexity low.
Solution Approach 2:
The air supply fan acts as an intermediary element between the heater and the environment. By controlling fan speed, the system can achieve fine-grained control of heating output without directly controlling heater power. This intermediary approach protects the relay from frequent switching while maintaining simple heater control.
3Power
If the heater capacity is selected according to maximum air volume, then the heating demand at maximum air volume is met, but wasteful power consumption occurs when operated at smaller air volumes
Solution Approach 1:
The patent applies dynamics by making the air supply fan speed variable. The control unit adjusts fan speed to match the actual heating demand, ensuring that the heater operates efficiently at any air volume level. This dynamic adjustment eliminates wasteful power consumption by matching heater output to actual needs rather than always operating at maximum capacity.
Solution Approach 2:
The patent changes the operating parameters by introducing variable fan speed control. Instead of fixed fan operation, the control unit dynamically adjusts fan speed parameter based on actual heating requirements. This parameter change ensures optimal energy efficiency across all operating conditions, preventing wasteful power consumption.
4Temperature
If the heater-off threshold temperature is set to prevent excessive temperature increase, then temperature control is improved, but chattering in turning-on and turning-off of the heater occurs
Solution Approach 1:
The patent applies dynamics by introducing variable fan speed control instead of relying solely on heater on/off control. The control unit dynamically adjusts fan speed to modulate heating output, creating a smooth transition that prevents chattering. This dynamic approach maintains stable temperature control without frequent heater switching.
Solution Approach 2:
The air supply fan serves as an intermediary control element between the heater and the thermal environment. By adjusting fan speed, the system can achieve fine-grained temperature control without directly switching the heater on and off frequently. This intermediary mechanism eliminates chattering while maintaining precise temperature 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
Prevents excessive air temperature increases and reduces wasteful power consumption by optimizing heater usage and air flow management, ensuring efficient heat exchange and extended component lifespan.
Implementation Method 1
a heat exchanger provided in a middle of the air supply passage and the air exhaust passage to perform heat exchange between the supply air flow and the exhaust air flow
Implementation Method 2
a heater that heats the supply air flow flowing through the air supply passage into the heat exchanger
Data Source
AI summary
A heat-exchange ventilation device includes: a heater connection terminal to which an external connection heater is connected; a temperature sensor that measures a temperature of a supply air flow passing through an air supply passage; and a control unit that controls operations of an air supply fan and an air exhaust fan and turning-on and turning-off of the external connection heater based on a measurement result of the temperature sensor. The external connection heater is installed in an outdoor air-supply duct and heats a supply air flow flowing through the air supply passage into a heat exchanger. The air supply fan is operable at a plurality of intensities, and the control unit prohibits a state in which the air supply fan is operated at an intensity lower than an intensity set in advance and the external connection heater is turned on.