Series-Coupled Dual-Thermistor Sensor for HVAC Subcool Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional HVAC systems require a large number of temperature sensors and complex controller hardware to measure temperature differences, making it impractical and expensive, especially for systems with multi-circuited coils.
Innovation Solution
A dual-thermistor sensor with a single signal output is used to measure temperature differences, such as superheat and subcool, by positioning thermistors at different locations within the coils and coupling them electronically in series, reducing the need for multiple signal inputs and processing resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensors and controller hardware are used to measure temperature differences, then measurement precision is maintained, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines two separate temperature sensors into a single integrated sensor assembly where both sensors share a common housing, mounting structure, and signal processing circuitry. This merging reduces the number of discrete components, simplifies controller hardware requirements, and lowers manufacturing complexity while maintaining the capability to measure temperature differences for superheat and subcool calculations
Solution Approach 2:
The integrated sensor assembly is designed to perform multiple functions: it simultaneously measures temperatures at two different locations (evaporator and condenser sides), provides differential temperature measurement capability, and interfaces with the controller through a unified signal connection. This multi-functionality reduces the need for separate dedicated hardware for each measurement function
2Measurement precision
If multiple temperature sensors are deployed to measure superheat and subcool, then measurement precision is achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges two temperature sensors into a single manufacturable unit with shared housing, mounting brackets, and electrical connections. This consolidation reduces the number of individual parts that need to be sourced, assembled, and tested, thereby lowering manufacturing cost while preserving the precision temperature measurement capability needed for superheat and subcool determination
3Measurement precision
If conventional sensor systems are used in multi-circuited coils, then measurement precision is maintained, but the number of sensors and hardware inputs increases
Solution Approach 1:
The integrated sensor assembly is designed as a universal measurement unit that can be deployed across multiple circuits in multi-circuited evaporator and condenser coils. Each assembly contains two temperature sensors that can monitor both the evaporator and condenser sides, allowing a single type of multi-functional sensor to replace what would otherwise require multiple single-function sensors across different circuits
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 allows for accurate measurement of temperature differences using fewer electronic signals, reducing hardware costs and complexity, and enabling more efficient monitoring and optimization of HVAC system performance.
Implementation Method 1
a first thermistor positioned to sense a saturated liquid temperature of a refrigerant flowing in a first portion of a condenser coil
Implementation Method 2
a second thermistor sensor positioned to sense a liquid temperature of refrigerant flowing in a second portion of the condenser coil
Implementation Method 3
temperature differences between the refrigerant flowing in different portions, or regions of these coils, can be used as a metric of the performance of the HVAC system
Data Source
AI summary
A condenser coil of a system includes a subcool sensor. The subcool sensor includes a first thermistor positioned to sense a saturated liquid temperature of refrigerant flowing in a first portion of the condenser coil. The subcool sensor includes a second thermistor positioned to sense a liquid temperature of the refrigerant flowing in a second portion of the condenser coil. The second thermistor is coupled electronically in series with the first thermistor. The subcool sensor includes a signal output for transmitting a subcool signal from the subcool sensor. The signal output is coupled electronically to a first terminal of the first thermistor and a second terminal of the second thermistor. A controller of the system includes an input/output interface which receives the subcool signal from the subcool sensor and determines a temperature difference between the saturated liquid temperature and the liquid temperature based on the subcool signal.