Vehicle Air Conditioner Evaporator Bypass for Dew-Point Heating
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Solution Overview
Problem
Vehicle air conditioners using vapor compression refrigeration cycles often waste energy due to the refrigerant evaporation temperature at the evaporator being unable to be set lower than the dew-point temperature of the air, leading to unnecessary heat exchange and potential frost formation.
Innovation Solution
A vehicle air conditioner system that includes a refrigerant flow-rate control mechanism, dew-point temperature detection, and a determination system to reduce the refrigerant flow rate when the dew-point temperature is below a threshold, and an evaporator temperature determination system to set a target refrigerant-evaporation temperature based on dehumidification load, preventing frost formation and optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the refrigerant evaporation temperature is set lower than the dew-point temperature to enable dehumidification, then dehumidification performance is improved, but frost formation occurs on the evaporator
Solution Approach 1:
The system dynamically adjusts the refrigerant evaporation temperature parameter based on the dew-point temperature of incoming air. When dew-point temperature is high, the evaporation temperature is set lower than dew-point to maximize dehumidification. When dew-point temperature is low (below threshold), the evaporation temperature is set higher than dew-point to prevent frost formation, thus adapting parameters to operating conditions
Solution Approach 2:
The patent implements dynamic control of the refrigerant flow rate and evaporation temperature based on real-time detection of dew-point temperature. The system transitions between different operating modes (dehumidification mode vs. cooling mode) depending on whether the dew-point temperature exceeds a predetermined threshold, making the system responsive to changing environmental conditions
2Object-affected harmful factors
If the refrigerant evaporation temperature is set higher than the dew-point temperature to prevent frost formation, then frost-free operation is achieved, but dehumidification performance deteriorates
Solution Approach 1:
The system changes the refrigeration cycle operating parameters (evaporation temperature, refrigerant flow rate) based on the detected dew-point temperature. When dew-point is below threshold, parameters are adjusted to operate above dew-point temperature, sacrificing some dehumidification capacity to prevent frost
Solution Approach 2:
The patent extracts the dehumidification function from the mandatory evaporator operation. When dew-point temperature is low, the system bypasses the evaporator or reduces refrigerant flow through it, separating the cooling function (still provided by evaporator) from the dehumidification function (omitted when unnecessary), thus avoiding frost while maintaining cooling
3Temperature
If the refrigeration cycle operates continuously to cool air, then cooling performance is maintained, but energy is wasted when dehumidification is not needed
Solution Approach 1:
The system applies partial refrigeration cycle operation by controlling refrigerant flow rate through the evaporator. When dew-point temperature is below threshold, the system reduces or stops refrigerant flow through the evaporator (partial action), maintaining only the necessary cooling function while eliminating excessive dehumidification action that would waste energy
Solution Approach 2:
The system periodically assesses the dew-point temperature and adjusts refrigerant flow accordingly. The refrigeration cycle operates in a periodic manner, alternating between full dehumidification mode (when dew-point > threshold) and reduced-mode operation (when dew-point ≤ threshold), optimizing energy consumption based on actual dehumidification needs
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 solution effectively prevents energy wastage by reducing unnecessary heat exchange and ensures efficient dehumidification, even when the refrigerant evaporation temperature cannot be lower than the dew-point temperature, thereby enhancing the overall performance of the air conditioning system.
Implementation Method 1
an evaporator for evaporating refrigerant
Implementation Method 2
serving as a heat exchanger for cooling air to be blown into an interior of a vehicle
Implementation Method 3
the refrigerant evaporation temperature at the evaporator being unable to be set lower than the dew-point temperature of the air
Data Source
AI summary
When a refrigerant evaporation temperature of an interior evaporator cannot be set lower than a dew-point temperature of air flowing into the interior evaporator in a heating operation, a refrigerant circuit is switched to a normal heating operation mode in which a flow rate of the refrigerant flowing into the interior evaporator is set to zero by allowing the refrigerant to flow toward a bypass passage. In a case where the air cannot be dehumidified by the interior evaporator, an unnecessary heat exchange between the air and the refrigerant in the interior evaporator can be suppressed. Thus, the energy of the vehicle air conditioner can be effectively prevented from being wasted.