Heat Exchanger Control Using Motor Data to Eliminate Flow Meters
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Solution Overview
Problem
Existing heat exchanger control systems are not independent of inlet stream temperature changes and require flow meters, which increase costs and reduce reliability.
Innovation Solution
A control unit with temperature sensors on the primary and secondary streams, and a pump connected to a motor, where the control unit calculates and regulates heat flow independently of primary and secondary liquid temperature and flow changes, using temperature and motor data to estimate flow rates and control heat flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flow meter is used to measure flow rate, then measurement precision is improved, but device complexity and cost increase, and reliability decreases
Solution Approach 1:
The patent removes the flow meter from the system entirely. Instead of measuring flow rate directly, the system infers flow rate from pump operational parameters (motor power consumption, revolutions per minute) stored in memory. This extraction of the flow meter eliminates the reliability issues and cost problems associated with flow meters while maintaining the ability to calculate heat flow.
Solution Approach 2:
The patent introduces pump operational parameters as an intermediary to indirectly determine flow rate. Rather than directly measuring flow with a flow meter, the system uses motor power consumption and RPM as intermediate measurements that can be correlated to flow rate through stored pump characteristics, achieving the same goal through a different measurement path.
2Ease of operation
If temperature difference control is used, then temperature control is simplified, but heat flow control becomes dependent on inlet stream temperature changes
Solution Approach 1:
The patent changes the control parameter from temperature difference alone to a combination of pump operational parameters (power, RPM) and temperature difference. By incorporating multiple parameters into the heat flow calculation, the system can independently control heat flow delivery without being solely dependent on inlet stream temperature variations.
Solution Approach 2:
The system continuously monitors pump operational parameters and temperature measurements, feeding this data back to the control unit which calculates actual heat flow and adjusts pump operation accordingly. This feedback loop enables the system to maintain independent heat flow control by compensating for inlet temperature changes through active adjustment of pump parameters.
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
Enables independent heat flow control and improved zone temperature control quality, allowing for early detection of heat exchanger malfunctions and efficient energy usage monitoring.
Implementation Method 1
Heat from a heat source is transported through a distribution network into terminal heat exchangers, where it is delivered
Implementation Method 2
Heat transfer liquid temperature
Implementation Method 3
there is a pump connected to a heat exchanger. A liquid mass flow through the pump
Implementation Method 4
there is a temperature sensor mounted on a primary stream inlet and outlet
Data Source
AI summary
A heat exchanger control and diagnostic apparatus includes a heat exchanger having a primary inlet of a primary heat-transport liquid mounted with a first temperature sensor and a primary outlet of the primary heat-transport liquid mounted with a second temperature sensor, wherein the primary outlet is piped to a pump, the pump comprising a pump impeller connected to a motor, the primary heat-transport liquid being piped by plumbing from the pump impeller to a heat source and from the heat source back to the primary inlet, and a control unit connected to the heat exchanger and the pump and comprising a motor control unit bi-directionally connected to the motor. The heat exchanger has a secondary inlet for a secondary heat-transport liquid and a secondary outlet ducted to a temperature zone and back to the secondary inlet, the control unit being augmented by a temperature module, the temperature module having a first input connected by a communication channel to an output of the temperature sensor, and a second input connected by a communication channel to an output of the second temperature sensor, the temperature module having an output for outputting a primary inlet temperature connected to one input of a power calculation module, and an output for outputting a primary outlet temperature connected to another input of the power calculation module, the power calculation module having a third input connected to a flow estimation module, one input of the flow estimation module being connected to an output of a memory unit, and another input being connected by a bus to an output of the motor control unit, an output of the power calculation module for outputting a heat flow estimate being connected to one input of a heat flow controller, and another input of the heat flow controller for inputting a heat flow demand being connected to an output of an operator unit, and an output of the operator unit being connected to an input of the motor control unit.