The investment in new refrigeration equipment is one of the largest capital commitments that a cold store or freezer operator can make. There is always pressure to figure out how to minimize the “sticker shock” associated with the project cost. Careful purchasing can pay dividends, but there is always the risk that a false economy will result in a significantly higher spend over the life of the project.
It can be difficult to get a hard-pressed project manager to care about this. They will be measured on the bottomline cost of their project, and usually the operating cost doesn’t feature highly in their thinking during the planning stages; they just want a lower capital expense figure.
There are several ways that they can get their life-cycle cost approach wrong, with expensive consequences, but also many ways to save money without courting disaster.
Don’t economize on the operating performance of evaporators and condensers by undersizing them. Putting in air-coolers that are too small could result in operating a low suction pressure that could easily add 10% to 15% to the annual electric bill. It might knock $50,000 off the project cost but will add more than that every year to the energy tab. Turning that around, who wouldn’t want a payback of less than a year on an energy saving measure?
Don’t skimp on maintenance access provisions that will result in lack of attention to the condition of equipment. If it requires a lot of effort to arrange a mobile platform to clean condensers then they are likely to operate in a dirty condition more than you might think. This may not have an obvious effect for most of the year, although energy consumption could again be higher than it ought to be, but when the hot summer weather comes the plant may be unable to cope. The cost then is the consequence of cooling plant failure and all the panic response that follows, in addition to the hike in annual energy cost.
Don’t economize on other health and safety issues through the project or in the operation of the plant. The danger of something going wrong and resulting in serious injury or worse, coupled with the business disruption and irreparable damage to reputation that follows all such incidents, simply isn’t worth it.
Having said that, do take stock of the true nature of the cooling requirements and ensure that the plant is not oversized for the job required. This might involve installation of modular systems that can be extended as the business grows, or it could simply be a modest increase in the size of a cold water buffer tank to enable a smaller chiller to be specified. Even the use of one size larger diameter chilled water pipe can provide useful buffer capacity and save on capital plant cost.
Do ensure that sufficient measures are included for performance measurement, even if this is only the provision of pockets for temperature probes and a few pressure gages. The number of systems that are “flying blind” with no way of knowing how well they are performing is really quite depressing, when for a few dollars more some simple metrics could have been included.
Do take every possible measure to minimize the heat load imposed on the refrigeration system. We ought to measure buildings and production systems on the basis of the amount of cooling required divided by the minimum necessary to achieve the output. Currently, this is only done for data centers with the power usage factor (the total amount of electricity used divided by the amount used by the computers). How about introducing a refrigeration usage factor along similar lines?
Most importantly, do specify the plant in sufficient detail to ensure you get what you need, and then hold the project team to account to make sure you really get it.