Method for starting a circulation pump and related circulation pump
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Solution Overview
Problem
Circulation pumps in heating and cooling systems face challenges in achieving stable and controlled start-up behavior, particularly when temperature conditions change, leading to inefficient operation and potential energy losses, due to direct dependence on secondary temperatures which can result in undesirable setpoints and reduced performance.
Innovation Solution
The method involves operating the circulation pump in a start-up phase with a constant speed or unregulated mode, transitioning to normal operation when a temperature criterion is met, using media temperature evaluation to ensure stable system conditions, and employing a limit value based on historical temperature data to prevent nonsensical setpoints and ensure energy-efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the circulation pump is operated with differential temperature control during start-up phase, then the pump speed is adjusted based on temperature difference, but the system produces undesirable setpoints and unstable operation when temperatures are equal or temperature difference is zero
Solution Approach 1:
The control system dynamically switches between two operating modes: during start-up phase when temperature difference is zero or small, the pump operates in uncontrolled mode with constant speed; after switchover to normal operation, differential temperature control is activated. This dynamic transition resolves the contradiction by adapting the control strategy to the current operational state, ensuring stability during start-up while maintaining energy efficiency during normal operation.
Solution Approach 2:
The system performs preliminary action by operating the pump in an uncontrolled mode during the start-up phase before differential temperature control is activated. This preliminary operation allows the system to establish stable flow conditions and avoid the problem of zero temperature difference causing undefined setpoints, after which the pump is switched to controlled mode when normal temperature conditions are achieved.
2Reliability
If the circulation pump operates in uncontrolled mode during start-up phase, then stable operation is achieved, but energy efficiency is reduced due to constant high speed operation
Solution Approach 1:
The system dynamically transitions from uncontrolled constant-speed operation during start-up to controlled differential temperature operation after switchover. This dynamic adjustment allows the pump to operate at high speed initially to ensure stable start-up and flow establishment, then automatically reduces speed to energy-efficient levels when normal temperature conditions are achieved, resolving the contradiction between start-up stability and energy efficiency.
Solution Approach 2:
The control system implements periodic action by defining a specific start-up phase with uncontrolled operation, followed by a switchover event that transitions to controlled operation. This time-based periodic control structure ensures that energy-intensive uncontrolled operation is limited to the necessary start-up period only, after which energy-efficient controlled operation takes over, balancing reliability and energy consumption.
3Use of energy by moving object
If differential temperature control is activated immediately at pump start-up, then energy efficiency is optimized through temperature-based speed adjustment, but the system produces nonsensical setpoints when flow temperatures are equal
Solution Approach 1:
The control system dynamically determines the operational state based on temperature conditions and switches between uncontrolled and controlled modes accordingly. This dynamic state determination adds a simple decision logic layer that prevents nonsensical setpoints by detecting when temperature difference is zero or insufficient, thereby avoiding the need for complex calculations while maintaining energy efficiency during normal operation.
Solution Approach 2:
The system performs preliminary action by establishing a start-up phase with uncontrolled operation before activating differential temperature control. This preliminary uncontrolled operation avoids the problem of zero temperature difference causing undefined setpoints, and the switchover to controlled mode occurs only when normal temperature conditions are achieved, simplifying the control logic by using temperature conditions as a clear transition criterion.
Data Source
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AI summary
The invention relates to a method for operating a controlled circulation pump (1) in a heating or cooling system, which is intended to operate in controlled normal operation using at least one medium temperature of a heat transfer medium of the heating or cooling system. After being switched on, the circulation pump (1) is operated differently in a start-up phase than in the normal operation following the start-up phase, wherein at least one medium temperature is determined during the start-up phase and a switch from the start-up phase to normal operation occurs when at least one temperature criterion taking the medium temperature into account is met. The invention further relates to a circulation pump for carrying out the method.