Air Conditioner Dew Point Control Without Outlet Humidity Sensors
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Solution Overview
Problem
Conventional air-conditioning systems face high costs and maintenance challenges due to the use of dew point temperature detectors, and humidity detectors can fail at high relative humidity, leading to false detection and reduced lifespan.
Innovation Solution
An indoor unit that calculates the dew point temperature of outlet air without using a dew point temperature detector or humidity sensor, utilizing a blower, evaporator, suction air temperature and humidity detectors, and a controller to adjust compressor frequency for precise dew point control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dew point temperature detector is installed at the outlet to control dew point temperature, then dew point control accuracy is improved, but device cost and maintenance complexity increase
Solution Approach 1:
The patent creates a virtual copy of the dew point detection function by calculating dew point temperature from measured parameters (temperature, humidity, enthalpy) rather than using a physical dew point detector. This mathematical model replicates the detection capability without the hardware complexity
Solution Approach 2:
The patent introduces enthalpy as an intermediary parameter to bridge the relationship between temperature, humidity, and dew point. By measuring these intermediate parameters and using thermodynamic relationships, the system indirectly determines dew point temperature without direct detection
2Measurement precision
If a humidity sensor is used at the outlet to monitor air conditions, then humidity detection capability is improved, but reliability decreases due to false detection and reduced lifespan at high relative humidity
Solution Approach 1:
The patent replaces the unreliable outlet humidity sensor with a combination of temperature and enthalpy measurements that do not suffer from the same reliability issues. The system uses robust temperature sensors and calculates humidity parameters mathematically rather than using physical humidity sensors in the harsh outlet environment
Solution Approach 2:
The patent replaces the physical humidity sensing mechanism with a thermodynamic calculation approach. By measuring temperature and enthalpy and using psychrometric relationships, the system substitutes mechanical/electrical humidity sensing with mathematical computation, eliminating sensor reliability issues
3Measurement precision
If temperature and humidity detectors are installed at the outlet to monitor air quality, then air condition control precision is improved, but device cost increases
Solution Approach 1:
The patent makes the enthalpy detector serve multiple functions: it provides enthalpy measurement for dew point calculation, and can also be used for general air quality monitoring and control. This multi-functionality eliminates the need for separate dedicated detectors for different parameters
Solution Approach 2:
The patent merges the dew point detection function with existing temperature and enthalpy measurement systems. By combining these measurements and using thermodynamic relationships, the system achieves dew point control precision without requiring additional specialized detectors
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
This approach reduces costs and improves reliability by eliminating the need for expensive detectors, while maintaining accurate dew point control, thus enhancing the air-conditioning system's performance and user friendliness.
Implementation Method 1
an evaporator, a blower that is configured to supply air to the evaporator
Implementation Method 2
controls a dew point temperature of the air (hereinafter, refer to as outlet air) blown out from the indoor unit
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
To provide a low-cost and highly reliable indoor unit and an air-conditioning apparatus having the same by obtaining a dew point temperature at the outlet side without installing a humidity sensor and a dew point temperature detector at the outlet side. An indoor unit 1 includes: an evaporator 1, a blower 1, a suction air temperature detector 6 that detects a suction air temperature at the upstream side of an air flow of the evaporator 3, an outlet air temperature detector 5 that detects an outlet air temperature at the downstream side of the air flow of the evaporator 3, an evaporator inlet fluid temperature detector 14 that detects a fluid temperature at the fluid inlet side of the evaporator 3, an adjustment valve 9 that adjusts a flow amount of the fluid made to flow into the evaporator 3, and a controller 4 that calculates a suction air dew point temperature by suction air temperature information detected by the suction air temperature detector 6 to calculate an outlet air dew point temperature based on the suction air dew point temperature, the suction air temperature, the outlet air temperature, and the evaporator inlet piping temperature.