Plastics Technology

MAY 2012

Plastics Technology - Dedicated to improving Plastics Processing.

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energy miser Cooling Water: Minimize Demand By Reducing Heat Gains By Robin Kent, Tangram Technology Ltd. In March, we introduced the subject of en- ergy savings through cooling-water manage- ment. The first stage in such a program is to minimize the demand, and the first step there is to reduce heat gains. Reducing heat gains will minimize the cooling load and can have a large impact on the running costs of any installation. Simply by identifying the heat loads and reducing these, it is possible to make major improvements to energy efficiency. The important thing is the water temperature at the operat- ing process and not the temperature as it leaves the chiller. There are two main areas for improvement: 1) Minimizing parasitic loads by insulating pipes, tanks and other compo- nents. This is particularly relevant where chilled-water pipes and pumps are in hot service areas, but heat gains can occur on any long pipe run where there is inad- equate insulation. 2) Minimizing unwanted heat gains by providing chilled water only to areas where it is actually needed. Fig. 1: Surveying your chilled-water piping with a thermographic camera is an easy way to spot vulnerabilities to parasitic heat gain. Here, some piping is insulated (lower and right areas), but the uninsulated area (middle left) shows up colder than the insu- lated areas. That's where heat gain will cost you energy and money. INSULATE CHILLED-WATER SUMPS Chilling water to the correct temperature and then pumping it to a poorly insulated or uninsulated sump for storage or distri- bution is simply throwing away energy (and money). The water will warm up in a poorly insulated sump and the energy used to chill the water beforehand will be wasted. All chilled-water sumps should be well insulated to prevent para- sitic heat gain. Simple retrofitted insulation can easily achieve this. This type of project will have a payback of around one year. rTip: Check the insulation levels of all your chilled-water sumps. This can be done by hand (feel for cold spots) or more accurately with a thermal camera. rTip: Apply or refurbish insulation as required to eliminate cold spots. rTip: Don't forget to check that the tops of the sumps are in place, well fitting, and adequately insulated. Fig. 2: Visible condensation on uninsulated chilled-water pipe indicates parasitic heat gain. 54 MAY 2012 PLASTICS TECHNOLOGY INSULATE CHILLED-WATER PIPING Chilled-water piping is often left uninsulated in an attempt to reduce initial installation costs. This may save money in the short term but the chiller system will just have to work harder and use more energy to get the chilled water to the process at the right temperature. In the long term, leaving piping uninsulated will cost more than if it was done right in the first place. If insulation is not

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