Heating/cooling balance

Prepare solution of items 10 to 13 by heating, cool and mix with solution balance of formulation. 

The heat balance on the bubble phase in Figure 4.24 that is assumed to be in plug flow mode and to have a negligible rate of reaction, as well as a negligible heat transfer with the heating/cooling coil, leads to... 

The cooling water (or other medium) must absorb enough heat to balance the heat of vaporization and condensate subcooling. Piping and hot wells must be sized based upon the maximum condenser requirement. The following example illustrates the method of calculating the quantity of cooling water for a specific service. 

Define the dry-bulb temperature, wet-bulb temperature, and humid volume of humid air. Given values of any two of the variables plotted on the psychrometric chart (dry-buib and wet-bulb temperatures, absolute and relative humidity, dew point, humid volume), determine the remaining variable values and the specific enthalpy of the humid air. Use the psychrometric chart to carry out material and energy balance calculations on a heating, cooling, humidification, or dehumidification process involving air and water at 1 atm. 

However, describing the chemical reactor performance under industrial operation conditions the heat balance is normally dominated by the heat of reaction term, the transport terms and the external heating/cooling boundary conditions, hence for chemical processes in which the phase change rates are relatively small the latent heat term is often neglected. 

In particular cases, considering extremely exothermic or endothermic processes, a global CSTR heat balance may be employed to determine a uniform operating temperature and the necessary heating/cooling capacity. 

First, the chapter lists the possible unit operations in the Aspen Plus Model Library, because the process is a connected set of the units. Then an example process is illustrated that makes ammonia from nitrogen and hydrogen. You will be able to get both the mass balances and the energy balances for the process. With this information you can determine the size of most of the equipment needed, and hence its cost. You can also determine the operating cost for heating, cooling, compression, and other tasks. The process involves a... 

Hence, when designing a plug-flow reactor with a heating/cooling fluid whose temperature varies, we have to solve either Eq. 7.4.3 or 7.4.5 simultaneously with the design equations and the energy balance equation of the reactor. 

Solve the design equations simultaneously with the energy balance equation, and, if necessary, the energy balance equation of the heating/cooling fluid to obtain Z s, 9, and 9 as functions of the dimensionless space time, t. 

Present the heat quantity balance pattern in winter and summer for underground cooling and heat utilization. 

Perform energy and material balances in unit operations with chemical reactions, separations, and fluid transformations (heating/cooling, compression/ expansion),... 

This principle can be illustrated by two jugglers balanced on a the ends of a seesaw. If one juggler drops some balls, then the other must throw some over to keep the seesaw even. A chemical reaction at equilibrium is also like a seesaw Removing a product causes the reaction to shift and produce more product. If the reaction is highly exother-mic (a word invented in this era to describe reactions that produce heat), cooling it removes this heat and causes the reaction to produce more product and heat. 

Humans, like other warm-blooded animals, have internal thermal regulatory systems. To be comfortable, the rate at which the body produces metabolic heat must balance with heat lost to the surrounding environment. If one loses heat too quickly, one becomes cold. If one loses heat too slowly or if the environment adds heat to the body, one becomes hot. The human body has limited means for adjusting the rate of heat loss. Sweating can increase the rate of cooling. Increased blood flow near the skin can also affect heat loss a little. To slow heat loss, the body may reduce peripheral blood flow and produce shivering. 

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