Supply temperature

The analysis of the heat exchanger network first identifies sources of heat (termed hot streams) and sinks (termed cold streams) from the material and energy balance. Consider first a very simple problem with just one hot stream (heat source) and one cold stream (heat sink). The initial temperature (termed supply temperature), final temperature (termed target temperature), and enthalpy change of both streams are given in Table 6.1. 

Stream Supply - temperature (°C) Target temperature (°C) J. Heat capacity flow rate (MW°C b... 

Provide Only the Heating or Cooling Actually Heeded. Generally, the supply temperature of hot and cold air, or water, should be reset according to actual need. This is especially important on systems or 2ones that allow simultaneous hea ting and cooling. 

FIG. 8 50 Manipulating heat flow linearizes the loop and protects against variations in supply temperature. 

The thermocycle system can be operated only when condensing water is available at a temperature lower than the required chilled-water-supply temperature. Modifications for a centrifugal refrigeration unit include the installation of a small liqmd-refrigerant pump, cooler spray header nozzles, and a vapor bypass line between the cooler and the condenser. Without the compressor operating, a thermocycle capacity up to 35 percent of the refrigeration-unit rating can be produced. 

During the 4 hr hot no-load test the oil supply temperature shall be varied 10°F above and 10°F below the normal oil supply temperature to demonstrate stability of the rotorbearing system. 

Stream Rowrate > specific heat Btu/hr °F Supply temperature, °F Target temperature, °F Enthalpy change lb Btu/hr... 

Given a VOC-laden gaseous stream whose flowrate is G, supply compositimi of the VOC is y and supply temperature is T , it is desired to design a cost-effective condensation system which can recover a certain fraction, a, of the amount of the VOC contained in the stream. 

A gaseous emission has a flowrate of 0.02 kmole/s and contains 0.014 mole fraction of vinyl chloride. The supply temperature of the stream is 338 K. It is desired to recover 80% of the vinyl chloride using a combination of pressurization and cooling. Available for service are two refrigerants NH3 and Nj. Thermodynamic and economic data are provided by problem 10.1 and by Dunn etal. (1995), Design a cost-effective energy-induced separation system. 

To determine the supply temperature of the curtain, 0g, and the thermal capacity P, we use... 

In practice, the air density has to be corrected for the specific supply temperature by... 

If a heat exchanger is added at low pressure ratio (Fig. 3.4b) then the mean supply temperature is greater than that of the (CHTX)r cycle whereas the temperature of heat rejection will be the same as in the [CHTXJr cycle. Therefore the efficiency of the [CHTHTXJr cycle is greater than that of the [CHTXJr cycle. 

Example 24.2 A building requires 500 kW of heating. Air enters the heater coil at 19°C at the rate of 68 kg/s. What is the air-supply temperature ... 

When the cooling load is smaller than the heating load, the 3-way valve at the inlet of secondary cooling pumps allows mixing of the supply and return water to maintain the design cooling supply temperature to the load. 

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