Water Pump Speed Control for Low-Energy Air Conditioning Circulation
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Solution Overview
Problem
In central air conditioning installations, the water pump constantly operates to maintain water flow, even when energy supply matches load-side energy consumption, leading to wasteful electric power consumption due to excess motor capacity and inefficient operation.
Innovation Solution
A method to control the water pump's operation by adjusting the motor's revolutions based on temperature variations and outdoor conditions, using an inverter to optimize energy supply and reduce motor demand, by calculating and applying specific revolution rates (N1 and N2) during heating and cooling modes, and disengaging the heat source when energy is no longer needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the water pump operates constantly to maintain water flow, then the water circulation is ensured, but the motor consumes electric power in vain when energy supply matches load-side energy consumption
Solution Approach 1:
The pump motor operates dynamically with two distinct revolution states (N1 and N2) rather than constantly at fixed speed. The control device switches between high-speed operation during heat source operation and low-speed operation during heat source stop, adapting the pump speed to actual system needs and eliminating wasteful energy consumption.
Solution Approach 2:
The pump motor operates periodically with alternating high-speed and low-speed phases corresponding to heat source operation cycles. During heat source operation, the pump runs at high speed (N1); during heat source stop, it runs at low speed (N2) to maintain minimum circulation. This periodic operation pattern eliminates continuous full-power consumption.
2Power
If the motor is selected with 20% surplus capacity for stationary operation, then the driving capacity is sufficient, but the surplus capacity increases wasteful electric power consumption
Solution Approach 1:
The motor operates at two distinct revolution levels rather than continuously at maximum capacity. The control device adjusts motor speed to match actual demand: high speed (N1) when full capacity is needed during heat source operation, and low speed (N2) when only minimum circulation is needed during heat source stop, eliminating wasteful consumption of surplus capacity.
Solution Approach 2:
The motor operating parameter (revolution speed) is changed between two states: N1 during heat source operation and N2 during heat source stop. This parameter change allows the motor to deliver full power when needed while consuming minimal power when only maintaining circulation is required, optimizing the utilization of motor capacity.
3Productivity
If the pump operates at maximum capacity, then the water flow is sufficient, but the electric power consumption is excessive when full flow is not needed
Solution Approach 1:
The pump operates dynamically with high-speed mode (N1) when maximum water flow is required during heat source operation, and low-speed mode (N2) when only minimum circulation is needed during heat source stop. This dynamic adjustment ensures sufficient productivity when needed while minimizing energy consumption during maintenance phases.
Solution Approach 2:
The pump performs partial action at low speed (N2) during heat source stop, providing just enough water circulation to maintain system readiness without the excessive action of full-capacity operation. This partial operation maintains necessary functionality while dramatically reducing energy consumption.
Data Source
AI summary
A method for controlling the operation of a cooled or heated water pump of an air conditioning installation is provided in which the flow rate of cooled or heated water is controlled to correspond to variations of energy demand on a load side unit. This can be effected by controlling on the basis of the temperature of the cooled or heated water the state of operation of a heat source, and the number of revolutions of the motor for driving the pump. When the temperature of the cooled or heated water is within a predetermined range of temperature and the operation of the heat source is halted, the motor is operated to rotate a number of revolutions N2 determined by a unit for controlling the rotation of the motor based on conditions obtained at a time of halting the operation of the heat source, until the temperature of the cooled or heated water reaches a predetermined value.