Maybe it is because I was born in Yorkshire or perhaps because it is in the DNA of engineers but, whichever, I cant stand waste – whether it is energy, kit or cash – or a combination of all three! My firm belief is that time spent in working out the right match, not necessarily the cheapest or most expensive, of systems design and components to the task repays the customers investment many, many times over.
Industrial refrigeration units are a case in point – where a modest investment in my expertise and some quite inexpensive controls can yield major savings. Perhaps because these units are peripheral to whatever production process is the core purpose of the facility the opportunity is often overlooked. It is a truism that there is very little that cannot be improved upon in this life and if it can, safely and within worldwide legislation, it should be.
Compressors on refrigeration units are large, are big energy consumers and often have fairly crude controls giving plenty of opportunity to improve the situation. The two key factors in refrigeration are pressure and temperature. The cycle for cooling starts with the refrigerant as a gas that is converted to liquid under pressure, back into gas and so on. A by-product of the cooling process is heat. There is therefore a necessity to dissipate heat generated by the process as well as limit the effect of ambient heat on the system. This is generally carried out by a series of fans operating to cool the heat exchangers.
A good example is a recent project I carried out for the major milk processor for UK supermarkets. Here there were 3 refrigeration units each using about £25000 worth of energy at £0.06p per kwh, a cost to the business of about £75k per year. In simple terms, Heat exchangers maximum efficiency requires a temperature differential 10 to 12 degrees above the average ambient. In the UK this is normally considered to be 18ºc. This would indicate a system setting of 30ºc. Tables for the gas used will show what pressure is required to deliver a given pressure – in this case 10 bar.
By suggesting and implementing a control system that replaced the old and fairly inaccessible manual controls with sensors that measured and controlled both pressure and temperature providing a much more refined degree of control over the activity of the fans, the business achieved payback on their investment with me within the first year.
It just shows the benefits to be gained by taking a closer look at the detail behind standard solutions.
Follow Tim!