Alternate source for chiller

Technical information Chillers MIXED ENERGY SOURCE CHILLER SYSTEMS


For small systems of water cooling (less 800-1000 tonnes), lower average cost of operation of electric drive chillers tend to exclude the alternative sources of energy considerations. However, for large enterprises, especially where the electrical load of the high fees, have the potential for use in acquisitions and/or motor drive units as part) mix.

As discussed in sec. 1, as absorption refrigerating machines and engines-ROM chillers are less efficient than electric drive chillers and, as a rule, have higher operating and maintenance expenses. However, if the seasonal cooling load profile such that the higher cost of cooling methods can be used for a limited number of hours to reduce peak demand and related responsibilities, requirements, usually imposed on an annual basis, the result is a saving of operating costs. The first step in determining if the source of energy, in addition to electricity should be considered, to understand electric utility rate schedules and costs of alternative fuels.

All electric rates to split the cost distribution of the two components of demand and consumption.

Demand, in terms of kW, represents the highest use of electricity for a certain period of time, usually 15 to 30 minutes for each month of the accounting period. Consumption in kWh, the total electricity consumption in the month billing period.

For power companies, the demand charge represents the cost incurred by the enterprise in with enough capacity to meet each clientsec maximum demand, even if the maximum may be needed only for a limited number of hours each year. In essence, it is a tool's try to evenly distribute the cost of capital for the recovery of its plants, power transmission lines, substations and other topics that require the presence of this potential.

For most electrical utilities, their peak demand occurs in the summer, because of conditioning use. Thus, the demand charge is calculated not only on the basis of the maximum use of electricity each month, these costs may be imposed on an annual basis using a ratchet provisions in electric prices.

Typical ratchet proposal will determine billing demand in each month, as the increase in real demand incurred during that month or the maximum demand incurred in the previous 11 months. Other rates may only use 80% ratchet, configuring the billing demand in each month, as the increase in real demand incurred during that month, or 80% of maximum demand, incurred in the previous 11 months. Some summer peak winter peak load and requires to determine the minimum demand in each month.

To further address the impact of the customers peak demand for utilitys system demand, peak and off-peak periods are typically specified using the utility on a daily basis. For example, the utility detects them in the peak summer period is from 10 AM till 8 PM, Monday to Friday, during June, July, August and September. During peak period, demand expenses may exceed $20.00 per kW, while off-peak demand charges can be only $3.00 to$4.00.

In addition, utilities create additional peak period, the value of penalties by establishing higher consumption expenditure during peak periods relative to off-peak periods. Power can be $0.14/kWh of energy during peak period, but only $ 0.04 during the peak period.

Cooling system because of their high demand and, respectively, low energy consumption, especially a bad influence on electric utilitys overall load factor (ratio of peak power average power required). By reducing peak load imposed on the electrical or shifting cooling energy consumption in peak periods, the user effectively help the utility to increase its load factor. It may be reflected in the rate schedules and conditions of the contract, as may be agreed with the utility can reduce the total cost of the production of chilled water.

The most common approach to the reduction of electric energy costs for cooling is an alternative source of energy during peak periods. Alternative energy sources that can be considered for use in a mixed source of energy, chiller system include the following:

1. Natural Gas and/or fuel oilNatural gas can be used in a direct-fired absorption chillers, less spark ignition engine drive chillers, or very large gas turbine units. в„– 2 fuel oil can be used in a direct-fired absorption chillers and diesel drive chillers.

Natural gas rate schedules are divided into two General categories: firm tariffs for gas and interrupted gas prices. The firm gas prices are based on utility gas is available at any time, regardless of the load on the gas-distributing system. Interruptible rates used in the facility allows the gas to cut off their gas supply during peak load distribution. Firm price of gas, as a rule, much higher than dashed rates. As the gas utility has its peak load distribution in the winter, gas used during the summer, even if purchased under non-guaranteed speed, very reliable source of energy.

For the majority of gas supply, summer load distribution is much less than their winter load balancing and has a great economic advantage, gas, if he can add summer load without increasing winter maximum. Cooling is the ideal candidate for additional summer load and, therefore, some utilities will offer discounts on the purchase of summer gas.

Fuel oil, as a rule, it is only important if the fuel storage facilities already created to serve boilers and/or emergency generators. Costs and environmental considerations associated with large fuel storage facilities are significant and tend to exclude this option for new installations.

Fuel oil purchased in bulk lot (as a rule, tanker load about 8000 liters) on place market. Thus, the head of the company should always shop for the best prices.

2. District Steam or High-Temperature Hot WaterLarger campus facilities such as universities, military bases, and hospitals may, steam or high-temperature hot water heating distribution systems. Since these systems with a small load during summer or steam or hot water can be used in absorption chillers to provide chilled water during peak periods.

The cost of steam or high temperature hot water should include the cost of fuel, discounted at the shooting inefficiency and distribution losses in the system. In the summer of COPs for the Central boiler plant can be 0.5-0.7; so careful studies are needed to determine the real value of steam or hot water supplied to the chiller(s).

3. Waste Heat from Industrial ProcessesHeat, if it is hot, and, if available in the necessary quantities, can be used to produce steam or high-temperature hot water for absorption cooling.

As discussed in sec. 1, в„– cooler type is more efficient than electric drive hmm. In addition, acquisitions and motor chillers cost more than the equivalent electric-drive chiller, to purchase and install. So, the economic feasibility of using alternative fuels depends on the use of inefficient, high-cost cooling method within a relatively short period of time to save up for the peak and ratchet electric charges associated with such a sum of the electric drive cooling to pay for the increased capital requirements within a reasonable timeframe.

As a rule, this does not happen if the cost of alternative energy sources is very low or additional cooling capacity is required anyway and only the incremental increase in the prices of alternative fuel systems should be restored. In the first case, the cost of energy should be checked and assessment of its reliability. In the second case, the capital costs of the difference between electric and absorption chillers or motor drive coolers should be defined. In any case, careful analysis is required...

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