Heating cost

Heat pumps are particularly suitable for recycling heat energy in the chemical-process industries. For the outlay of an additional fixed-capital expenditure Cec on a heat-pump system, a considerable reduction in the annual heating cost can be effected. 

Let us consider a process unit requiring heat at the rate of Qo GJ/h operating for y h in a year. We shall let the unit cost of this base heating requirement be Cg per gigajoule. Therefore the annual heating cost for this unit is Qoy s por year. 

The annual cost of heat delivered by the heatpump is Qoy o, where the unit cost Cd is given by Eq. (9-240). Therefore, the annual saving on heating costs in dollars per year is Qoyi B d), which can also be written in terms of Eq. (9-238) as W(COP) y(cg — c ). 

The payback period in years for a heat-pump system is the additional feed-capital cost Cpc divided by the annual saving on heating costs. This can be written as... 

Gas Caloric Heating Cost Basis Evaluation for Liquids Recovery... 

Reaction rates almost always increase with temperature. Thus, the best temperature for a single, irreversible reaction, whether elementary or complex, is the highest possible temperature. Practical reactor designs must consider limitations of materials of construction and economic tradeoffs between heating costs and yield, but there is no optimal temperature from a strictly kinetic viewpoint. Of course, at sufficiently high temperatures, a competitive reaction or reversibility will emerge. 

The remaining liquid flows continuously to a pit outside the house and is pumped in a silo. The fertilizer value is low. Daily removal of faeces and urine promotes as well a better house climate as a lower odour emission in comparison with piggeries with underslat slurry storage. Installing this filtersystem in partly slatted floor houses straw can be used to improve animal comfort, and to reduce heating costs. 

The large cell used for the electrolysis of sodium chloride in industry is known as a Downs cell. To decrease heating costs, calcium chloride is added to lower the melting point of sodium chloride from about 800°C to about 600°C. The reaction produces sodium and calcium by reduction at the cathode, and chlorine by oxidation at the anode. 

The operating cost of Electro VAC can be significantly higher than other soil heating systems that use fuel heating, electrical heating costs about seveu times more than fuel heating. 

Figure 6. The effect of feed concentration on the cost of product water at various heat costs as compared to membrane and freezing processes for feed water at 25° C., in 10,000,000-gallon-perrday plant...

The mixture of zinc vapour and carbon monoxide passes through an oudet near the top of the furnace and the zinc metal cools and condenses. The heating costs of the furnace are reduced by burning the carbon monoxide which is produced. 

In the winter months, significant benefits are derived from the use of concretes that contain cold-weather accelerating (CWA) admixtures with antifreeze properties. The economic benefits are derived from their ability to eliminate heating costs, afford the use of less costly mixes and enable the extension of the construction... 

Temperatures up to 1500 °C reduce the reversible thermodynamic potential for water decomposition from a room temperature value of 1.23 V to 0.7 V (43%). The cost of electrolytic hydrogen varies linearly with the potential of the cell at the current density being used, since cost of the electricity is the dominating item in the cost of electrolytic hydrogen, high-temperature steam electrolysis would greatly improve the economics. Heat is needed to maintain the temperature of the system, but heat costs only a third of the cost of electricity. So far, very high temperature cells are research items, but 1000 °C cells have been developed in Europe under the nickname Hot Elly. ... 

Cast Aluminum MGO 650 F 35 Uniform heat Cost, Low temperature... 

In temperate and cold regions structures of nearly all kinds require good thermal insulation to reduce heating costs. In the construction industry, thermal insulators made from materials such as fiberglass and foamed plastics have been used widely because they are noncrystalline and incorporate a large void space with high entrapped air content. 

Because of nonequilibrium boiling conditions in a simple distillation, the vapors may not contain the true azeotrope, and the heat cost may be too high. Therefore a column is still used to rectify the exact azeotrope at the head of the column however, only a few trays are required. 

Continuous distillation always gives a better, more uniform product at a lower heat cost and usually a lower plant cost. A continuous operation is essential in azeotropic distillation when an entrainer is added, or it would necessarily have to be fractionated off to reuse it after each batch. 

It should be apparent that insulation does not eliminate heat transfer it merely reduces it. The thicker the insulation, the lower the rate of heat transfer but also the higher the cost of insulation. Therefore, there should be an optimum thickness of Insulation that corresponds to a minimum combined cost of insulation and heat lost. The determination of the optimum thickness of insulation is illustrated in Fig. 7-38. Notice that the cost of insulation increases roughly linearly with thickness while the cost of heat loss decreases exponentially. The total cost, which i.s the sum of the insulation cost and the lost heat cost, decreases fir.st, reaches a minimum, and then increases. The thickness corresponding to the minimum total co.st is the optimum thickness of insulation, and this is the recommended thickness of insulation to be installed. 

Reconsider Prob. 9 -25. In order to reduce lire heating cost of the hot water, it is proposed to insulate the sirte and bottom surfaces of the container with 5-cm-thick fibergla.ss insulation k = 0.035 W/m °C) and to wrap the insulation with aluminum foil (e = 0.1) in order to minimize the heat loss by radiation. An estimate is obtained from a local insulation contractor, who proposes to do the insulation job for 350, including materials and labor. Would you support lliis proposal How long will it take for the insulation to pay for itself from the energy it saves ... 

Reconsider Prob. 9-32, To reduce the heating cost of the pipe, it is proposed to insulate it with sufficiently thick fiberglass insulation (fe = 0.035 W/m C) wrapped with aluminum foil (e = 0.1) to cut down the heat losses by 85 percent. Assuming the pipe tempeialuic to remain constant at 25 C, determine the ihickne.ss of the insulation that needs to be used. How much money will Ihe insulation save during this 10-h period Anmers 1.3 cm, 22.3... 

Increase in heating costs — (Heating load inctease)(Unit cost of fiiel)/ntficiency = (377.7 thenns/year)(S0.50/thenn)/0,80 = 236/year... 

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