Refrigeration, air-conditioning and cooling technology - 2007.pdf

PLH_KKK_32_85.QXP 25.05.2007 10:11 Uhr Seite 83Economical consideration in theselection of fittingsDifferent components always belong to a coldwaterinstallation which must be planned anddimensioned specifically for fulfilling the posedair-conditioning or cooling tasks - each separately,especially in interconnected systems.The engineer must also consider the economicconstraints at an early point in time. On the onehand, the investment costs, and on the otherhand, also the later operating costs and measureswhich minimise these. Here, the respectiveefficiencies of the components and of the overallsystem play a decisive role: Because, dependingon the load status (full load / partial load) ofthe system, the efficiencies can vary, which hasa negative effect on the energy demands andthe operating costs.What options are there for optimisation? Howcan one manage such problems and keep themunder control, both in planning and operation?Let's consider the circuit between the watercooler and the load points. The transport ofthe cooling water from the water cooler to the"users", such as the RLT devices, fan coils, coolingfans, etc. is done by circulating pumps.Here, the cold water is to be distributed accordingto utilisation by dimensioning the pipelines(cross-sections) and control valves. Fundamentally,when dimensioning, a minimum and maximumdimensioning value result, which dependson the investment and operating costs. Low investmentcosts often involve small cross-sectionsin the pipes and fittings with relativelysmall pump connections. This solution, however,brings about high pressure losses in the watersupply network, and the resulting high operatingcosts. Conversely, however, higher investmentcosts don't automatically mean lower operatingcosts!CapacitorsRefrigeratingmachinen=konst.VaporiserPrimary circuit(Generator part)6°C12 °CBased on the specific demands of the specifiedmodel system, it will be shown that, in practice,components are often planned for the hydraulicnetwork which aren't absolutely necessary.This often occurs due to ignorance and incorrectlyunderstood safety thinking. Also, this oftenresults in considerable and "avoidable" operatingcosts. The main task is to consider allcomponents with regard to their behaviour innormal operating situations and the costs theyinvolve. This is that much more important sinceall these costs make Germany a very highlypriced place to do business. The example can beapplied to every production, administration orresidential area. The physical and economicalpreconditions are identical. A basis for planningcooling water distributor systems will be presentedwhich will guarantee functionally safeand economic systems in the future.Secondary circuit(Load part)MMWilo Planning Guide - Refrigeration, air-conditioning and cooling technology 02/2007 83