Hot Water Control Using CHP Storage and Anti-Reversal Valve Logic
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Solution Overview
Problem
Existing hot water systems with combined heat and power (CHP) units face inefficiencies due to frequent switching of boilers to maintain temperature, leading to damage and increased fuel consumption, especially when heat demand fluctuates, and the use of large diameter pipes complicates the installation of one-way valves to prevent flow reversal.
Innovation Solution
A hot water system with temperature sensors and a control valve that adjusts flow based on measured temperatures to prevent flow reversal and maintain optimal heat distribution, using a control system with a neutral and proportional band to regulate the valve's operation, allowing for efficient operation of CHP units and secondary heating devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the boiler is operated to augment CHP heat output when heat demand exceeds CHP production, then the heat demand is met, but the boiler frequently switches on and off causing damage and inefficiency
Solution Approach 1:
The system introduces a hot water store that accumulates heat in advance when CHP production exceeds demand, preparing hot water reserves before they are needed. This preliminary action allows the boiler to operate continuously at stable temperatures rather than frequently cycling on and off to meet fluctuating demand, thereby resolving the contradiction between meeting heat demand and maintaining boiler operational stability
Solution Approach 2:
The hot water store acts as an intermediary buffer between the CHP unit and the heating system. It decouples the CHP heat production from the immediate heat demand, allowing the boiler to maintain stable operation while the store absorbs temperature fluctuations. This intermediary element prevents direct transmission of demand variability to the boiler, eliminating frequent switching cycles
2Use of energy by moving object
If the boiler pre-heats water to meet heat demand, then heat efficiency improves, but condensation in condensing boilers is prevented reducing overall efficiency
Solution Approach 1:
The system performs preliminary heating action by storing hot water when CHP production is high, rather than continuously pre-heating water before each heating cycle. This allows condensing boilers to operate in their efficient condensing mode for longer periods while still meeting heating demands through the stored hot water, resolving the contradiction between pre-heating efficiency and condensing efficiency
Solution Approach 2:
The system implements periodic heating cycles where the boiler operates intermittently to refill the hot water store rather than continuously pre-heating water. This periodic operation allows the condensing boiler to maintain optimal operating temperatures for condensation to occur, while still providing adequate hot water supply through the accumulated reserves in the store
3Stability of the object's composition
If a one-way valve is installed in the main water circuit to prevent flow reversal, then flow control improves, but the large pipe diameter makes valve installation difficult and expensive
Solution Approach 1:
The system extracts the flow control function from the main water circuit by implementing separate controlled connections between the heating device water circuit and the main circuit. Instead of installing a large one-way valve in the main circuit, the system uses independently controllable valves at the connection points, eliminating the need for difficult-to-install large-diameter one-way valves while maintaining flow direction control
Solution Approach 2:
The system introduces controlled connection points as intermediaries between the heating device water circuit and the main water circuit. These connection points use manageable-sized valves to control flow direction and prevent reversal, avoiding the need to install large one-way valves directly in the main high-diameter water circuit, thereby resolving the installation difficulty while maintaining flow control stability
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 reduces the frequency of boiler switching, prevents overheating, and enhances efficiency by ensuring that the CHP unit operates continuously while the secondary heating device operates for extended periods, minimizing fuel consumption and extending the lifespan of system components.
Implementation Method 1
The controller has two sensor inputs, the sensor inputs comprising a first temperature sensor input to measure a temperature in the heating device water circuit and a second temperature sensor input to measure the temperature of the main water circuit
Implementation Method 2
a valve for controlling flow of water from the heating device water circuit output to the main water circuit
Implementation Method 3
the control system is arranged to determine an operational set point based on the temperature of water that can be supplied by the heating device water circuit. The valve may then be controlled to maintain the water in the main water circuit downstream of the heating device water circuit output at the operational set point
Data Source
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AI summary
A water heating apparatus for supply of heated water to an installation comprises a combined heat and power (CHP) unit, a heat storage means, and a secondary heating device. The CHP unit and the secondary heating device are arranged to operate in a first mode where the CHP unit provides heat to the heat storage means and the secondary heating device provides all the heated water required to meet the heat demand of the installation; and to operate in a second mode where the secondary heating device is inactive, and the heated water to meet the heat demand is provided by the CHP unit and/or from the heat storage means.