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Uses of Cogeneration
Published in Bernard F. Kolanowski, Small-scale Cogeneration Handbook, 2021
Often, it may be just as practical to use the cogenerator’s hot-water system as a means to preheat the boiler feed water that is pumped into the boiler to make steam. A Btu is defined as the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. A boiler that produces 10,000 pounds per hour of steam usually raises the temperature of the incoming water to the boiling point and then adds additional heat for the steam pressure desired. Steam systems can be either once through, meaning the steam is released to atmosphere and lost; or as a return system where most, if not all, of the steam is returned to the boiler as condensate. In those cases, the temperature of the condensate is anywhere from 140°F To 180°F and must be raised to the boiling point and beyond. If the temperature can be raised 30 to 40 degrees by cogeneration, that is less fuel required by the boiler to produce steam. Therefore, a 10,000-pound-per-hour boiler will use 400,000 Btu of energy just to raise the condensate from 150 to 190 degrees Fahrenheit. A cogenerator producing 100 kW of electricity can also produce that 400,000 Btu of thermal energy as well.
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Published in Albert Thumann, Scott Dunning, Plant Engineers and Managers Guide to Energy Conservation, 2020
Henry M. Healey, Paul L. McCrone
In order to size the solar system, the daily water-heating load is required, a solar collector type and size must be selected, and the number of collectors required to meet the load are needed. In this example, 500 gallons of water are to be heated from 70 degrees to 130°F each day. The daily heat load on the water heater then would be approximately 250,000 Btu/day (500 gpd*8.34 lb/gal* 60°F)*1 Btu/(lb-°F). The selection of the type and size of solar collector is required. For low temperature water heating, a flat plate, single glazed solar collector with a selective (low emission) collector is recommended. Other collectors are available for various requirements as a function of collection temperature and climatic conditions. (See ASHRAE Systems Handbook, Chapter 33—Ref. 8—for additional information.) Once the collector type is selected, then the size of the array (number of collectors) can be determined.
Stand-Alone Photovoltaic Systems
Published in Roger Messenger, Homayoon “Amir” Abtahi, Photovoltaic Systems Engineering, 2017
Roger Messenger, Homayoon “Amir” Abtahi
Since it takes 1 BTU to raise the temperature of 1 lb of water by 1°F, and since 1 kWh is equivalent to 3413 BTU, one need simply convert the excess kWh to BTU. For example, in April, the excess 15.6 kWh will generate 53,243 BTU. With a cold water temperature of 55°F, heating a gallon of water to a temperature of 180°F will require 8.35 × 125 = 1044 BTU, since a gallon of water weighs 8.35 lb. Hence, the leftover 53,243 BTU is enough to heat 51 gallons of water to 180°F. Of course, if any heat is lost from the pot, then not all the available BTU will go into heating the coffee water, but even at 80% efficiency, 40.8 gallons of coffee should be enough to keep everyone happy, since this would be almost a gallon per day per person if four people stay 3 days/week.
Catalytic valorization of glycerol for producing biodiesel-compatible biofuel blends
Published in Biofuels, 2020
Husam A.M. Al-Mashhadani, Sergio C. Capareda, Ronald E. Lacey, Sandun D. Fernando
The results of all studies conducted show that it is possible to have an ether produced and used as a biodiesel additive with different blending ratios. Type and concentration of catalyst were major variables, which affected the reaction significantly. Temperature and reaction time can have a significant effect on the process as well. However, the energy content of the top phase, evaluated via heat of combustion (86,166 BTU/gal), was significantly lower than that of the control biodiesel (128,642 BTU/gal). The likely reason for this is the presence of water (a result of dehydration reaction as well as neutralization). Further miscibility studies confirmed the amphiphilic nature of the top phase – being miscible with water as well as biodiesel. This result presents advantages as well as challenges: the ability to blend with abstract water can be beneficial in a high-humidity environment by keeping the water as an emulsion in the fuel itself, disallowing phase separation in the fuel tank. However, the presence of water dramatically reduces the blend's energy content while also requiring an additional dewatering step, which is energy intensive.
Magnetorheological finishing of ball-cup surface using new tool to enhance ball-transfer-unit performance
Published in Materials and Manufacturing Processes, 2023
Ankit Aggarwal, Anant Kumar Singh
Furthermore, heat is generated as a result of friction and wear between the components of the ball transfer unit (BTU). This heat generation within the BTU leads to a rise in temperature. Thus, the rise in temperature in the BTU may deteriorate the BHBC surface by causing its premature breakage.[41] So, the reduction in heat generated (Hbtu) during BTU operation can take place by reducing the coefficient of friction (COF). The heat generation in BTU can be calculated using Eq. 11.[40]
Improvement of variable refrigerant flow system performance using energy saving control strategy and chilled water storage
Published in Science and Technology for the Built Environment, 2018
Xiaojie Lin, Jiazhen Ling, Yunho Hwang, Reinhard Radermacher, Byungsoon Kim
The simulated cooling season performances of the energy saving control strategy and conventional invariant control are shown in Figure 11. The set-point of the rooms was 25°C (77°F). The running period of the model was from July to September. The TMY3 weather data of Miami, Florida was used. As shown in Figure 11, by using the energy saving control strategy, the daily energy consumption is reduced. Overall, the seasonal energy consumption is reduced from 2899 kWh (9,891,799 Btu) to 2701 kWh (9,216,195 Btu) with energy saving of 6.8%.