Vehicle Cooling Humidity Estimation From Refrigerant State Data
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Solution Overview
Problem
Ambient relative humidity significantly impacts the required cooling power needed to cool a vehicle cabin, and existing systems lack effective methods to accurately estimate and adjust for humidity levels without direct sensors.
Innovation Solution
A method to estimate ambient relative humidity using a 2-zone moving boundary refrigerant dynamic model and a Kalman filter, combined with refrigerant pressure and temperature sensors, to adjust the operation of cooling system components like compressors and blowers for efficient cabin temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a direct humidity sensor is installed to measure ambient relative humidity, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses refrigerant pressure and temperature sensors as intermediary measurements to indirectly determine relative humidity. Instead of directly measuring humidity with a dedicated sensor, the system measures refrigerant state parameters (pressure and temperature) which are then used through thermodynamic relationships to infer humidity levels, thereby avoiding the need for complex and expensive direct humidity sensing hardware
Solution Approach 2:
The patent replaces the mechanical/physical humidity sensor with a computational approach using thermodynamic models and algorithms. The system substitutes direct physical measurement with mathematical calculation based on refrigerant cycle parameters, eliminating the need for specialized humidity sensing components
2Use of energy by moving object
If cooling system operation is adjusted based on accurate humidity estimation, then energy consumption is reduced, but measurement and estimation complexity increases
Solution Approach 1:
The patent implements a feedback control system where estimated humidity information is continuously fed back to adjust cooling system operation. The refrigerant circuit controller uses the estimated relative humidity to dynamically modify compressor, expansion device, and blower operations, creating a closed-loop system that optimizes energy consumption based on actual environmental conditions
Solution Approach 2:
The patent makes the refrigerant circuit controller multi-functional by enabling it to perform both refrigerant cycle control and humidity estimation functions. The same controller that manages compressor and expansion device operations also executes the humidity estimation algorithm and adjusts blower speed based on humidity levels, consolidating multiple functions into a single control unit
Data Source
AI summary
A method of operating a cooling system of a vehicle includes measuring a refrigerant pressure and a refrigerant temperature of a flow of refrigerant in a refrigerant circuit of the cooling system, estimating a relative humidity of a supply airflow across an evaporator of the refrigerant circuit utilizing the measured refrigerant pressure and the measured refrigerant temperature, and changing operation of one or more components of the refrigerant circuit as a result of the estimated relative humidity.