Humidity Control Air Routing to Prevent Compressor Liquid Return
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Solution Overview
Problem
The existing humidity adjustment devices face challenges in suppressing the return of liquid refrigerant during startup, leading to inefficiencies and potential damage due to excessive liquefaction and subsequent flow into the compressor.
Innovation Solution
The device incorporates a refrigerant circuit with two heat exchangers and a four-way switching valve, which determines the temperature of outside and room air to route air through the appropriate heat exchanger as an evaporator or condenser, preventing excessive cooling and liquefaction, and maintains the electronic expansion valve in a communicating state during shutdown to manage refrigerant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fan is driven to force outside air and room air into the humidity adjustment device at startup, then temperature measurement can be performed, but the evaporator temperature becomes excessively low causing excessive refrigerant liquefaction
Solution Approach 1:
The patent applies preliminary action by controlling the air circulation switching device to supply higher temperature air to the evaporator before the compressor starts operating. This preliminary temperature control prevents excessive refrigerant liquefaction that would otherwise occur when low temperature air is supplied at startup, thereby avoiding liquid refrigerant return to the compressor.
2Productivity
If low temperature air is circulated through the evaporator at startup, then dehumidification efficiency is improved, but excessive refrigerant liquefaction occurs
Solution Approach 1:
The patent applies dynamics by making the evaporator air supply dynamic rather than static. The air circulation switching device dynamically adjusts which air source (outside air or room air) is supplied to the evaporator based on temperature conditions. At startup, higher temperature air is supplied to prevent excessive liquefaction, while during normal operation, lower temperature air can be supplied to maximize dehumidification efficiency.
3Loss of energy
If the electronic expansion valve is closed during shutdown, then refrigerant flow is stopped, but lubricating oil is lost to the evaporator
Solution Approach 1:
The patent applies preliminary action by maintaining the electronic expansion valve in a communicating (open) state during shutdown before the system stops completely. This preliminary positioning of the expansion valve prevents lubricating oil from being carried to the evaporator by refrigerant flow, thereby preserving lubricating oil in the compressor for subsequent startup operations.
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 effectively suppresses the return of liquid refrigerant to the compressor during startup, reduces lubricating oil loss, and optimizes the determination of higher air temperatures for efficient operation, thereby enhancing the device's performance and longevity.
Implementation Method 1
an amount of a refrigerant resulting from liquefaction of the evaporated refrigerant in the evaporator becomes larger
Implementation Method 2
an adsorbent fixed to it, which, at temperatures equal to or lower than a predetermined temperature, performs an adsorption action of absorbing water
Implementation Method 3
the outside air is forced into the inside of the room through one of the heat exchangers
Data Source
AI summary
When a humidity adjustment device starts up, an outside air temperature To and an room air temperature Tr are compared to determine which air temperature is higher. By mutually changing the flow of the outside air and the flow of the room air by means of an air circulation switching device, the air having the higher temperature of the outside air and the room air is circulated to a heat exchanger that operates as an evaporator.