Stratification storage water heater
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Solution Overview
Problem
Storage water heaters face challenges in efficiently storing thermal energy and reducing heat standing losses, especially when responding to signals from the electricity grid or adapting to surplus renewable energy.
Innovation Solution
A heating system comprising a storage tank and an external heating apparatus with an inlet connected to the lower portion and an outlet connected to the upper portion of the tank, allowing for the recirculation of water to maintain the natural thermocline and adapt electrical power consumption based on available surplus power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the storage tank temperature is increased to deliver more hot water, then the volume of hot water delivered is increased, but heat standing losses increase
Solution Approach 1:
The storage tank is divided into two distinct zones: an upper hot water zone and a lower cold water zone, separated by a thermocline. This segmentation allows the system to maintain a smaller volume of hot water at high temperature (reducing heat losses) while having access to a larger volume of cold water that can be heated on-demand or pre-heated, thus resolving the contradiction between delivering more hot water and minimizing heat standing losses.
Solution Approach 2:
The system pre-heats a portion of the cold water from the lower zone before it enters the hot water zone, or pre-heats water in anticipation of demand. This preliminary heating action reduces the thermal gradient and heat losses while ensuring sufficient hot water volume is available when needed, addressing both the volume delivery requirement and the heat loss reduction goal.
2Reliability
If heating elements are used to maintain high temperature in the storage tank, then hot water demand is met, but energy consumption increases during periods of low demand
Solution Approach 1:
The heating system dynamically adjusts its operation based on predicted demand and actual usage patterns. The controller modifies heating element operation, recirculation flow rates, and thermocline position in real-time, allowing the system to maintain reliability during high demand while minimizing energy consumption during low demand periods by reducing heating activity and maintaining stratification.
Solution Approach 2:
The system incorporates sensors and controllers that continuously monitor temperature, flow rates, and demand patterns. This feedback enables the system to learn from past events and adjust heating operations accordingly, ensuring hot water demand is met while optimizing energy consumption by avoiding unnecessary heating during periods when stored hot water is sufficient.
3Quantity of substance
If the thermocline position is lowered to increase hot water volume, then more hot water is available, but heat standing losses increase due to larger heated volume
Solution Approach 1:
Instead of maintaining a large volume of hot water in the tank, the system pre-heats water in the lower zone or pre-heats water before it enters the hot zone. This preliminary action ensures that when hot water is needed, sufficient volume is available without having to maintain a large hot water reservoir, thus reducing heat standing losses while meeting demand.
Solution Approach 2:
The system maintains continuous recirculation and partial heating of the thermocline region, ensuring that water is continuously prepared for hot water delivery. This continuous action allows the system to provide hot water volume on-demand rather than maintaining a large static hot water volume, reducing heat losses while ensuring availability.
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
The system enhances the capacity to store thermal energy, reduces heat standing losses, and allows for flexible power consumption adaptation, enabling effective demand response and self-consumption of surplus renewable energy.
Implementation Method 1
a heating apparatus (3, 30) external to the storage tank (2, 20), the heating apparatus (3, 30) having an inlet (331) connected to a lower portion and an outlet (332) connected to an upper portion of the storage tank (2, 20) so that a liquid thrust by a pressure difference may be withdrawn from the storage tank (2, 20), pass through the heating apparatus (3, 30) and be fed back into the upper portion of the storage tank (2, 20)
Implementation Method 2
An effect of this configuration is that the liquid in the storage tank may be heated starting from the top respecting and substantially guaranteeing the natural thermocline of the temperature of a liquid in the storage tank
Implementation Method 3
the liquid in the storage tank may be heated starting from the top respecting and substantially guaranteeing the natural thermocline
Data Source
AI summary
Disclosed is a storage water heating system with a heating apparatus external to the storage tank. The external apparatus receives a liquid coming from a lower portion of the tank, heats it, and delivers it to a top portion of the tank, where the hot water outlet is located. In this way, the natural thermocline of temperatures in the storage is maintained, the water delivered is at a greater temperature, efficiency is increased by reducing heat standing losses, and there is greater control over the quantity of energy stored. The external apparatus may be activated in response to a heating demand for the storage or for outlet water, or even in response to a power surplus from photovoltaic equipment and in the absence of withdrawal. A control system may modulate the power of the instantaneous water heater to track the surplus power of the photovoltaic system.