Recirculating fluid heating systems
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Solution Overview
Problem
Existing liquid heating systems for plumbing face challenges in efficiently maintaining hot water supply during peak demand without excessive size, cost, or energy consumption, as tank-type heaters deplete reserves and instantaneous heaters require high power, leading to increased costs and limited heating rates.
Innovation Solution
A modular liquid heating system with a reservoir, pump, and controller that allows heated liquid return to the reservoir, adjusting the heating rate and cold liquid intake to maintain setpoint temperature, ensuring efficient heating performance across varying flow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a tank-type heater is used to accumulate hot water reserve, then hot water supply during peak demand is improved, but device size, cost, and energy consumption increase
Solution Approach 1:
The system divides the hot water supply function into two parts: a storage reservoir that accumulates hot water and a recirculation loop that continuously circulates water through the heater. This segmentation allows the storage tank to be smaller while still meeting peak demand, as the recirculation system supplements the supply during high demand periods.
Solution Approach 2:
The system performs preliminary heating by continuously circulating water through the heater, so that hot water is always available in the recirculation loop. This eliminates the need for a large storage tank, as water is heated in advance and kept ready for immediate use during peak demand.
2Quantity of substance
If a tank-type heater is used to accumulate hot water reserve, then hot water supply during peak demand is improved, but energy consumption increases due to heat loss
Solution Approach 1:
The recirculation system continuously pumps water through the heater and back to the reservoir, maintaining a constant supply of hot water. This continuous circulation eliminates idle heat loss from large storage tanks, as the system only heats water that is actively being circulated and used.
Solution Approach 2:
The system recovers heat that would otherwise be lost by continuously circulating water through the heater. The recirculation loop captures and reuses thermal energy, preventing heat loss to the surrounding environment that occurs in traditional tank-type heaters.
3Volume of stationary object
If an instantaneous heater is used to heat water on demand, then device size and cost are reduced, but heating rate is limited by power supply
Solution Approach 1:
The system separates the heating function from the storage function, using a compact instantaneous heater for heating and a separate reservoir for storage. This allows the heater to be small while still providing sufficient heating capacity, as the reservoir accumulates hot water over time to meet peak demand.
Solution Approach 2:
The system performs preliminary heating by continuously circulating water through the compact heater, building up hot water in the reservoir over time. This allows a small heater to provide sufficient hot water during peak demand by heating water in advance and storing it.
4Volume of stationary object
If an instantaneous heater is used to heat water on demand, then device size and cost are reduced, but ability to meet peak demand is limited
Solution Approach 1:
The system divides the hot water supply system into a compact instantaneous heater and a separate storage reservoir. The heater provides continuous heating while the reservoir accumulates hot water, allowing the system to meet peak demand with a much smaller heater than would be required without storage.
Solution Approach 2:
The recirculation system performs preliminary heating by continuously pumping water through the instantaneous heater and storing it in the reservoir. This allows a small heater to provide sufficient hot water during peak demand by heating and storing water in advance.
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 effectively maintains hot water supply at setpoint temperature, reducing energy consumption and costs by optimizing heating rate and water distribution, preventing reserve depletion, and allowing for compact, cost-effective installation.
Implementation Method 1
a pump connected in series with the heater, whereby the pump can draw liquid from the reservoir and impel the liquid in a predetermined downstream direction through the heater
Implementation Method 2
the controller being operative to actuate the heater to supply heat to liquid passing from the inlet to the outlet so as to bring the liquid at the outlet to a setpoint temperature
Implementation Method 3
The return connection and pump desirably are constructed and arranged to permit liquid flow from the outlet of the heater to the reservoir but prevent liquid flow from the reservoir to the fixtures through the return connection
Data Source
AI summary
A liquid heating system includes an instantaneous heater (18) having an inlet (20) connected to a reservoir (62). The outlet (22) of the heater is connected to fixtures (72) which use the heated liquid, and is also connected through a return connection (30) to the reservoir. In an idle mode, a pump 40 draws liquid from the reservoir (62), so that the liquid circulates through the heater and back to the reservoir. A controller (52) actuates the heater to heat the liquid to a first setpoint temperature, so that the liquid in the reservoir stabilizes at the first setpoint temperature. In a supply mode, some or all of the heated liquid flows from the outlet to the fixtures (72). Cold liquid is admitted from a supply (60) to the reservoir, and cold liquid desirably also is supplied to the heater inlet along with liquid from the reservoir, so that the heater inlet receives a combination of these. The controller controls the proportion of cold liquid to liquid from the reservoir in the combination, so as to maintain the heater at a setpoint heating rate while also maintaining the temperature of liquid discharged from the heater outlet at or near a setpoint temperature.