Warewasher Heat Recovery Rinse Mixing for Faster Startup
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Solution Overview
Problem
Commercial warewashers with heat recovery systems face challenges in achieving desired operating temperatures during startup, as the exhaust system temperature is not sufficiently high initially, leading to excessive time required for the water to reach the desired temperature.
Innovation Solution
A heat recovery system with a control valve that selectively supplements the water exiting the heat recovery system with hot water from a hot water source, ensuring the water reaching the final rinse station is at the desired temperature by monitoring the temperature with sensors and adjusting the hot water input accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a heat recovery system is used to transfer heat from exhaust air to cold water, then energy efficiency is improved, but the time required for water to reach desired temperature during startup increases
Solution Approach 1:
A hot water tank pre-stores hot water before it is needed during startup conditions. This preliminary preparation of hot water allows the system to immediately supplement the heat recovery system's output when needed, rather than waiting for the heat recovery system to gradually heat the water from cold
Solution Approach 2:
The hot water tank acts as an intermediary between the cold water source and the final rinse system. During startup, it provides pre-heated water that supplements the heat recovery system's output, bridging the temperature gap until the heat recovery system reaches full effectiveness
2Temperature
If hot water is continuously supplied from a hot water source, then the desired temperature is maintained, but energy consumption increases
Solution Approach 1:
The system dynamically changes the temperature parameter of the water supplied to the final rinse system by mixing variable amounts of hot water from the tank with water from the heat recovery system. This allows precise temperature control that adapts to changing conditions rather than continuously supplying maximum hot water
Solution Approach 2:
Temperature sensors continuously monitor the water temperature and provide feedback to the control system. Based on this feedback, the control system adjusts the mixing ratio of hot water and heat recovery water, supplying hot water only when and to the extent needed to maintain the desired temperature
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 time needed for the final rinse water to reach the desired temperature during startup and maintains high temperature rinse performance, while also providing energy savings by optimizing the use of hot and cold water sources.
Implementation Method 1
A heat recovery system is located between the final rinse system and the cold water source. The heat recovery system transfers heat from the exhaust air to the cold water provided from the cold water source.
Implementation Method 2
A valve associated with the hot water source selectively supplements the water exiting the heat recovery system with hot water from the hot water source.
Data Source
AI summary
A warewasher for washing wares includes a housing defining an internal space with at least one spray zone for washing wares. A liquid delivery system provides a spray of liquid within the spray zone. A tank includes an inlet that is connected to a hot water source for filling the tank with hot water. The liquid delivery system receives water from the tank. An exhaust vents heated air from the housing. A final rinse system is connected to a cold water source. A heat recovery system is located between the final rinse system and the cold water source. The heat recovery system transfers heat from the exhaust air to the cold water provided from the cold water source. A valve associated with the hot water source selectively supplements the water exiting the heat recovery system with hot water from the hot water source.