Air-conditioning and ventilation apparatus
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Solution Overview
Problem
Conventional air-conditioning and ventilation systems fail to maintain indoor humidity within a comfortable range when dehumidifying heat-exchanged supply air, leading to excessive indoor humidity, user discomfort, and increased cooling loads, due to reliance on outdoor temperature-based control of air-conditioning coils without considering outdoor humidity.
Innovation Solution
An air-conditioning and ventilation apparatus that adjusts the cooling capacity of the air-conditioning coil based on both outdoor air temperature and humidity, using a control unit and outdoor-air temperature and humidity map to ensure the absolute humidity of supplied air is equal to or lower than the indoor target, thereby regulating dehumidification effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dehumidification control is executed based on outdoor temperature alone with fixed air-conditioning coil capacity, then dehumidifying function is performed, but blown-out temperature drops excessively causing dew condensation on blow-out grill
Solution Approach 1:
The control method changes from fixed capacity control to variable capacity control based on outdoor temperature and humidity conditions. The air-conditioning coil capacity is dynamically adjusted by changing refrigerant flow rate through expansion valve control, allowing the system to adapt cooling capacity to actual dehumidification needs and prevent excessive temperature drop
Solution Approach 2:
The system uses outdoor temperature and humidity sensors to provide feedback to the control unit, which then adjusts the air-conditioning coil capacity accordingly. This closed-loop control ensures the blown-out temperature remains above dew point while still achieving effective dehumidification
2Reliability
If dehumidification control is executed with 100% or fixed capacity of air-conditioning coil, then dehumidifying function is performed, but energy consumption increases unnecessarily
Solution Approach 1:
The system transitions from static fixed-capacity control to dynamic variable-capacity control. The air-conditioning coil operates at different capacities (e.g., 100%, 75%, 50%, 25%) based on real-time outdoor temperature and humidity conditions, allowing the system to consume only the necessary energy for effective dehumidification
Solution Approach 2:
The control method changes the operating parameters of the air-conditioning coil based on outdoor conditions. By adjusting refrigerant flow rate and coil capacity dynamically, the system achieves dehumidification with optimized energy consumption rather than running at fixed high capacity
3Ease of operation
If dehumidification control is executed without considering outdoor humidity, then simple control logic is maintained, but indoor humidity control precision deteriorates
Solution Approach 1:
The control unit receives feedback from both outdoor temperature and humidity sensors, as well as indoor humidity sensors. This multi-parameter feedback enables precise calculation of dehumidification requirements and dynamic adjustment of air-conditioning coil capacity to maintain indoor humidity within target ranges
Solution Approach 2:
The control unit calculates the required dehumidification capacity in advance based on outdoor temperature and humidity conditions before executing the dehumidification process. This preliminary calculation ensures precise humidity control from the start of operation
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 system effectively maintains indoor humidity within comfortable limits, reduces energy consumption, and prevents excessive cooling loads by dynamically adjusting the air-conditioning coil's cooling capacity in response to outdoor conditions, ensuring efficient and comfortable dehumidification.
Implementation Method 1
a heat exchanger (3) that performs heat exchange between supply air and exhaust air
Implementation Method 2
the heat-exchanged supply air is heated or cooled by the air-conditioning coil
Implementation Method 3
blown-out temperature of the ventilation and air-conditioning apparatus drops excessively, thereby causing dew condensation on a surface of a blow-out grill
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An air-conditioning and ventilation apparatus (50) includes an air-conditioning coil (7) that is installed on a downstream side of a heat exchanger (3) in a supply air trunk and can change cooling capacity with respect to heat-exchanged outdoor air in multiple stages; an outdoor-air temperature and humidity sensor that detects temperature and relative humidity of the outdoor air; and a control unit (23) that stores therein reference data in which the cooling capacity is set for each combination of temperature and relative humidity of the outdoor air such that absolute humidity of supply air becomes equal to or lower than indoor target absolute humidity on the basis of a dehumidification load corresponding to an absolute humidity difference between indoors and outdoors, and determines a cooling capacity value of the air-conditioning coil (7) on the basis of detection results during a cooling operation by the outdoor-air temperature and humidity sensor and the reference data.