15 May 2003
intercoolers will be used. Use capacity control methods to reduce energy consumption
as the load is reduced to minimize life cycle costs.
Helical Rotary (Screw) Compressor. Screw compressors will use oil
injection. An oil separator or sump and oil cooler will be included in the system. Oil
coolers assist the condenser in rejecting heat, so the refrigerant condenser can be
reduced in capacity equal to the amount of heat extracted by the oil cooler.
Electrical and Mechanical Drives. Base the choice of drives for
refrigeration equipment on the availability and price of fuel, cost of electricity, or the
capability of using waste heat. The operating characteristics of the refrigeration
compressor are typically a major factor in determining the compatibility of the drive and
5-2.4.1 In areas of high electric demand rates, evaluate the impact of air conditioning
of the facilities' peak electric demand to determine economic feasibility of electric drive.
Compare this to the cost per kWh, installation peak load, and any demand charges or
incentives provided by the utility serving the installation. Deregulation in the electric
utility industry may change the cost structure paid by the installation, so take into
account any known or potential changes that may result from deregulation.
5-2.4.2 Where steam turbine drives are used, evaluate using the exhaust steam of
non-condensing turbines as the input to low pressure steam absorption refrigeration in
the life cycle cost analysis.
5-2.4.3 Use only split-shaft gas turbines for air conditioning due to the poor starting
characteristics of single-shaft machines. Whenever gas turbines are used, evaluate
using exhaust gases to generate steam in a waste heat boiler to power absorption
refrigeration in the life cycle cost analysis.
5-2.5.1 Consider absorption equipment only where waste steam from incineration of
solid wastes, heat recovery engine or gas turbine exhausts, or exhaust from steam
5-2.5.2 Absorption chillers must have the capability of operating at variable
condenser water temperature without crystallization.
5-2.5.3 Use a throttling valve to modulate flow to the absorbent generator with chilled
water temperature, as well as an automatic steam valve that reduces steam pressure
and temperature, for energy efficient part load capacity control.
5-2.5.4 Consider using two-stage absorption refrigeration whenever high-pressure
steam or high-temperature water is available. The life cycle cost analysis will address
the economic feasibility of using the higher first-cost, two-stage machine.