A chiller is a mechanical device used to facilitate heat exchange from water to a refrigerant in a closed loop system. The refrigerant is then pumped to a location where the waste heat is transferred to the atmosphere. Programmable Logic Controller (PLC) is used to maintain automation in the system.
Design and Control of PLC based Chiller Automation System
A chiller is a mechanical device used to facilitate heat exchange from water to a refrigerant in a closed loop system. The refrigerant is then pumped to a location where the waste heat is transferred to the atmosphere. Programmable Logic Controller (PLC) is used to maintain automation in the system. PLC (programmable logic control) is an industrial digital computer which has been ruggedized and adapted for the control of power plants and process industries such as: chemical industry, textile industry, cement or any activity that requires high reliability control and ease of programming and process fault diagnosis.
In industries embedded based chillers are used that are very expensive and they require high maintenance therefore by using PLC there will be focus on to reduce cost of system and design a system that is easy to integrate. Chillers play important role to provide cooling service in the industry. Our visit to Colgate Palmolive. ltd at site kotri has illuminated these issues faced by industry regarding their production. Need of Chiller systems for industrial application is increasing exponentially because of the global warming and industrial heat which resists in natural cooling process of the system therefore we use chiller system in order to overcome the heat and cool the system with required temperature.
Chiller system has variety of applications from cooling to process uses such as it is used in injection molding machine, induction motor, Welding process and heavy generators. The final product will be a system that will absorb heat from source and transfer it to separate water source.
Following are the objectives of the project.
The design of PLC based chiller system is to introduce automation in the chilling process. In this system PLC is main part which is used to process the data and control the system. In general PLC based chillers system contains number of equipment like Compressor, condenser, evaporator, PLC, HMI etc. PLC based chiller system completely depends upon temperature, pressure and flow of fluid in accordance with the plant requirement. Temperature, pressure and flow are maintained in the plant using sensors and switches like Temperature Sensors, level sensors, pressure switch and flow switch which provide input to PLC and gives informative data about current temperature, pressure and flow. This information is used as data log on PLC and as feedback from plant to take necessary action. Depending on the input PLC provides output signals that can be digital or analog. PLC contains IO modules with interfaces, programming ports, memory. In this project we are using winproladder and DOPSoft software for the programming of PLC and HMI. Ladder language is one of the PLC programming language which is simple and widely used for PLC programming. The final outputs and control is carried out by HMI.
The defining characteristic of PLC enfolds on solving industrial automation logic problems more reliably and quickly. These fundamentals remain today. However, it does not mean end users should solely focus on these features. PLC have attained many advanced abilities, some of which can help solve merchandise problems or enhance applications.
There are some key benefits mentioned below:
The final deliverable project will be a control system that is used to control some different parameters of the chiller system such as: pressure, temperature, flow of fluid. The system also provides more user interface capabilities, among the ways to interface and program the PLC, one may use the program parameters such as set points, timer delays and use a PC running HMI software which provides a GUI (Graphical User Interface) or by use of dedicated HMI touch screen.
The deliverable product will be a prototype which will elaborate that functionality of the PLC based control system that how it will control and regulate the chiller system and to make the system as much easier and safe which can be controlled from any part of industry. This system also allows any other type of sensors to be integrated as per requirement of different companies with their different operational systems.

| Item Name | Type | No. of Units | Per Unit Cost (in Rs) | Total (in Rs) |
|---|---|---|---|---|
| Condenser | Equipment | 1 | 6000 | 6000 |
| compressor | Equipment | 1 | 3000 | 3000 |
| Evaporator | Equipment | 1 | 5000 | 5000 |
| Liquid line solenoid valve | Equipment | 3 | 1250 | 3750 |
| Liquid line shutoff valve | Equipment | 2 | 250 | 500 |
| Pressure switch | Equipment | 2 | 1500 | 3000 |
| ON/OFF switch | Equipment | 3 | 100 | 300 |
| Emergency switch | Equipment | 1 | 200 | 200 |
| Motor fan | Equipment | 1 | 1800 | 1800 |
| Temperature sensor | Equipment | 3 | 1000 | 3000 |
| Level sensor | Equipment | 1 | 1450 | 1450 |
| Flow switch | Equipment | 2 | 1500 | 3000 |
| Overload relay | Equipment | 1 | 1000 | 1000 |
| PLC | Equipment | 1 | 15000 | 15000 |
| HMI | Equipment | 1 | 12000 | 12000 |
| Circuit breaker | Equipment | 1 | 200 | 200 |
| Alarm | Equipment | 4 | 150 | 600 |
| Pump | Equipment | 1 | 4500 | 4500 |
| Light indicator | Equipment | 3 | 100 | 300 |
| Relay | Equipment | 3 | 500 | 1500 |
| Extra: wires, connectors,panal,base,pipes,clips | Equipment | 1 | 3500 | 3500 |
| Printing,Scanning,travel expenditure,other | Miscellaneous | 1 | 10000 | 10000 |
| Total in (Rs) | 79600 |
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