Refrigeration system control and protection device
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current refrigeration systems lack a reliable and cost-effective solution to protect compressors from liquid refrigerant flooding, crankcase heater malfunctions, and excessive superheat, with existing systems being complex, expensive, and requiring frequent calibration and maintenance.
Innovation Solution
A device utilizing two temperature sensors, one upstream and one downstream, to measure the temperature difference and prevent compressor operation when the difference drops below a predetermined level, integrated with a PID regulator to control the expansion valve and trigger defrost cycles, eliminating the need for sophisticated electronics and periodic calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sophisticated electronic control systems are used to detect liquid refrigerant flooding, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces sophisticated electronic detection systems with a simple temperature differential measurement system. By measuring the temperature difference between the suction line and the compressor inlet, the system detects liquid flooding without requiring complex electronics, capacitive sensors, or sophisticated signal processing circuits.
Solution Approach 2:
The patent uses inexpensive temperature sensors and a simple comparator circuit instead of expensive electronic control systems. The solution employs basic, readily available components that are cheap to replace if needed, rather than relying on complex electronic systems with long development cycles and high costs.
2Measurement precision
If sophisticated electronic control systems are used to detect liquid refrigerant flooding, then detection precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent substitutes complex electronic measurement systems with simple temperature differential measurement. The detection precision is achieved through straightforward temperature sensing and comparison, eliminating the need for expensive electronic controllers, capacitive sensors, or sophisticated signal processing hardware.
Solution Approach 2:
The system uses low-cost temperature sensors and basic electronic components that are inexpensive to manufacture and replace. The solution avoids expensive proprietary electronics, making the system economically viable for widespread installation on various compressor types.
3Reliability
If capacitance-based liquid detection systems are used, then liquid flooding detection is improved, but maintenance requirements increase
Solution Approach 1:
The patent replaces capacitance-based detection systems with simple temperature differential measurement. The system uses basic temperature sensors and a comparator that have no moving parts, no calibration requirements, and no periodic maintenance needs, unlike capacitive sensors that require recalibration and maintenance.
Solution Approach 2:
The temperature differential measurement system is inherently self-calibrating and requires no periodic maintenance. The system continuously monitors the temperature difference between two points and automatically detects liquid flooding conditions without requiring user intervention, calibration, or maintenance of sensitive electronic components.
4Reliability
If suction accumulators are installed to prevent liquid surge, then start-up protection is improved, but system complexity and cost increase
Solution Approach 1:
The patent replaces mechanical suction accumulators with an electronic control system based on temperature differential measurement. Instead of adding large mechanical components to the system, the solution uses simple temperature sensors and a comparator to detect and prevent liquid surge, maintaining system simplicity while providing effective protection.
5Reliability
If crankcase heater monitoring systems are installed, then heater malfunction detection is improved, but device complexity increases
Solution Approach 1:
The patent uses temperature differential measurement to indirectly monitor crankcase heater operation. By comparing the temperature at the compressor inlet with the suction line temperature, the system detects heater malfunction without requiring separate temperature sensors in the crankcase or complex monitoring circuits, keeping the system simple and reliable.
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
Provides reliable protection against liquid flooding and crankcase heater failures while preventing excessive superheat, offering a low-cost, maintenance-free solution suitable for all compressor types, including small and large units, by using differential temperature measurements that are stable and require no refrigerant-specific tables.
Implementation Method 1
a first temperature sensor that measures a temperature of a refrigerant gas downstream of the electric motor and the compressor body
Implementation Method 2
a second temperature sensor that measures a temperature of the refrigerant gas in a suction line of the compressor
Implementation Method 3
wherein the device detects a temperature difference between the first temperature sensor and the second temperature sensor
Implementation Method 4
integrated with a PID regulator to control the expansion valve and trigger defrost cycles
Data Source
Figure 1
Figure 2
Figure 3
AI summary
New device to protect a compressor against liquid flooding, oil heater malfunction, low refrigerant charge, high superheat. The system consists of a device that measures two temperatures separated by a heat source (The electric compressor or the suction heat exchanger or both). The temperature difference can detect a liquid return to the compressor, a high superheat, a low refrigerant charge or a crankcase heater malfunction and the temperature difference can control the electronic expansion valve.