Compressor Thermo-On Timing for Low-Load Air Conditioning
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Solution Overview
Problem
Air-conditioning apparatuses struggle to prevent prolonged compressor inactivity and excessive start-stop cycles when air conditioning load is low or exhaust heat is not returned to the indoor unit, leading to inefficient temperature control.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit and sensors that detect blowing temperature and suction temperature, using a compressor control unit to set a prohibited thermo-on time based on preceding operation states, such as continuous thermo-on time, compressor start-stop counts, blowing temperature rate, and suction temperature increase, to optimize compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor is controlled based solely on suction air temperature rise, then the number of compressor starts and stops is minimized, but the compressor does not start for a long time when air conditioning load is low or exhaust heat is not returned, causing blowing air temperature to exceed preset values
Solution Approach 1:
The system uses multiple feedback parameters including blowing air temperature, suction air temperature, continuous operation time, and start-stop frequency to dynamically adjust compressor control decisions, ensuring reliable temperature control while preventing excessive delays
Solution Approach 2:
The control system dynamically adjusts the thermo-on prohibition time period based on operating conditions such as continuous operation time and start-stop frequency, making the control strategy adaptive rather than fixed to respond to varying load conditions
2Manufacturing precision
If the compressor starts frequently to maintain blowing air temperature, then temperature controllability is improved, but the number of compressor start-stop cycles increases excessively
Solution Approach 1:
The system applies partial action by using multiple control parameters with different weights and thresholds, allowing temperature control precision without requiring full frequent starts, thereby balancing control accuracy with operational efficiency
Solution Approach 2:
The system performs preliminary assessment of multiple parameters (blowing temperature, suction temperature, operation time, start-stop frequency) before deciding on compressor start/stop, preventing unnecessary start-stop cycles while maintaining 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
This configuration prevents prolonged compressor inactivity and reduces start-stop cycles, ensuring efficient temperature control by approximating blowing temperature to a preset value, even under low air conditioning loads or when exhaust heat is not returned.
Implementation Method 1
a refrigerant circuit sequentially annularly connecting a compressor, a heat source-side heat exchanger, an expansion valve, and a use-side heat exchanger
Implementation Method 2
a refrigerant circuit sequentially annularly connecting a compressor, a heat source-side heat exchanger, an expansion valve, and a use-side heat exchanger
Implementation Method 3
a refrigerant circuit sequentially annularly connecting a compressor, a heat source-side heat exchanger, an expansion valve, and a use-side heat exchanger
Data Source
AI summary
An air-conditioning apparatus prevents a compressor from not starting for a long time when an actual air conditioning load is low or when exhaust heat from heat-generating devices in an air-conditioned indoor space is not returned to an indoor unit, and reduces the number of times the compressor is started and stopped. The air-conditioning apparatus includes a refrigerant circuit sequentially annularly connecting the compressor, a heat source-side heat exchanger, an expansion valve, and a use-side heat exchanger, a blowing temperature sensor detecting a blowing temperature of air brown into the air-conditioned indoor space after passing through the use-side heat exchanger in the indoor unit including the use-side heat exchanger, and a compressor control unit performing thermo-on and thermo-off controls to start and stop the compressor, to approximate the blowing temperature detected by the blowing temperature sensor to a preset temperature. A time for which the next thermo-on control is prohibited is set based on an air-conditioning operation state immediately preceding the thermo-off control or during thermo-off time.