Evaporative Heat Exchanger Control for Water-Saving Cooling
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Solution Overview
Problem
Existing heat exchange systems face challenges in efficiently cooling process fluids when ambient air temperatures are higher than the desired cooling temperature, requiring a balance between energy savings and water conservation while maintaining a constructively simple and inexpensive design.
Innovation Solution
A heat exchange apparatus featuring a heat exchanger with ventilation and evaporative means, where a temperature sensor controls the airflow and evaporative liquid supply to optimize cooling efficiency, using a combination of dry and adiabatic cooling modes to achieve energy and water savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If evaporative liquid is supplied to cool the process fluid when ambient air temperature is higher than desired cooling temperature, then cooling effectiveness is improved, but water consumption increases
Solution Approach 1:
The control system dynamically adjusts the evaporative liquid supply rate based on measured process fluid temperature and ambient conditions. When temperature exceeds the desired threshold, the system increases water supply to enhance evaporative cooling; when temperature is acceptable, it reduces or stops water supply, thereby optimizing cooling effectiveness while minimizing water consumption.
Solution Approach 2:
The system employs temperature sensors to continuously monitor process fluid temperature and uses this feedback to control the evaporative liquid supply. The control unit compares measured temperature against desired temperature and adjusts water supply accordingly, creating a closed-loop system that achieves effective cooling only when necessary, thus reducing overall water consumption.
2Temperature
If cooling gas flow rate is increased to cool the process fluid, then cooling effectiveness is improved, but energy consumption increases
Solution Approach 1:
The control system dynamically adjusts the cooling gas flow rate based on measured process fluid temperature and ambient air temperature. When the temperature difference between ambient air and desired cooling temperature is small, the system increases air flow rate to enhance cooling; when the difference is large, it relies more on evaporative cooling with reduced air flow, thereby optimizing cooling effectiveness while minimizing energy consumption for air movement.
Solution Approach 2:
The system dynamically switches between dry cooling (high air flow, no water) and evaporative cooling (lower air flow, water supplied) modes based on real-time temperature measurements and ambient conditions. This dynamic adjustment allows the system to use the most energy-efficient cooling method for each operating condition, reducing overall energy consumption while maintaining effective cooling.
3Productivity
If both evaporative liquid supply and cooling gas flow are optimized simultaneously, then cooling effectiveness and resource efficiency are improved, but device complexity increases
Solution Approach 1:
The control unit serves multiple functions: it reads temperature sensor signals, determines ambient and process fluid temperatures, decides between dry and evaporative cooling modes, controls evaporative liquid supply rate, and adjusts cooling gas flow rate. This multi-functional control approach integrates temperature optimization and resource efficiency control into a single system, achieving high cooling efficiency without proportionally increasing device complexity.
Solution Approach 2:
The system merges the control of evaporative liquid supply and cooling gas flow into a unified control strategy based on temperature measurements. Rather than having separate complex control systems for water supply and air flow, both parameters are adjusted together based on the same temperature feedback, simplifying the overall control architecture while achieving optimized cooling performance and resource efficiency.
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 cools process fluids by adjusting airflow and evaporative liquid usage based on temperature and humidity conditions, achieving efficient energy use and water conservation while maintaining a simple and cost-effective design.
Implementation Method 1
an evaporative body (generally a body made of a cellulose material, in particular formed in a shape of a panel) which is placed in the air flow before the heat exchanger and which is supplied with an evaporative liquid (water) in order to humidify and cooling the air, in particular to bring the ambient air to the wet bulb temperature
Implementation Method 2
a heat exchanger includes a pipe system in which a process fluid to be cooled flows and in which, when the temperature of gas usable for cooling (generally air at ambient temperature) is greater than the temperature at which the process fluid is required to cool
Data Source
Figure 1
Figure 2
AI summary
A heat exchange method and apparatus are described with a heat exchanger comprising an inlet and an outlet of a process fluid, ventilation means for generating a flow of a cooling gas, at least an evaporative body traversed by the flow before the heat exchanger, evaporative liquid supply means to wet the evaporative body, a temperature sensor for measuring the temperature of the process fluid at the outlet of the heat exchanger, control means controlling the flow rate of the evaporative liquid based on the temperature measured by the temperature sensor.