Cycling temperature

Fig. 8. Effect of heat rejection temperature and maximum cycle temperature on refrigeration COP...

The variation of refrigeration COP with heat rejection temperature (final bed adsorption temperature and condensing temperature are assumed equal) and the maximum cycle temperature is illustrated for an evaporating temperature of-5°C in Fig. 8. Heat pmnp COP s follow similar trends but are higher. 

Similarly, with cycling temperatures, large fast cycles can cause discomfort. To avoid this, if the time to complete one cycle is less than 15 minutes and the peak-to-peak temperature variation is greater than 1.1 °C, the average rate of temperature change should be less than 2.2 °C/h (Fig. 5.9). Very slow rates of temperature change dT/dt < 0.5 °C/h) are much less difficult to adjust to and the change can go unnoticed until the temperature is beyond the comfort zone temperature. 

Fig. 4.10 shows more fully calculated overall efficiencies (for turbine cooling only) replotted against isentropic temperature ratio for various selected values of Tj = T,.,. This figure may be compared directly with Fig. 3.9 (the a/s calculations for the corresponding CHT cycle) and Fig. 3.13 (the real gas calculations of efficiency for the uncoooled CBT cycle). The optimum pressure ratio for maximum efficiency again increases with maximum cycle temperature T. ... 

Alloy composition (%) Maximum cycle temperature ( C) Life to burn-out (s X 10 ) ... 

Temperature of Brazing Cycle and Flux. The brazing cycle temperature shall be limited to a maximum of 1,600°F (871 °C). The flux selection shall be active at 300°F (149°C) above the maximum filler metal liquidus. The temperatures shall be specified/qualified per BPS/PQR. 

Figure 6.3. Camot cycle temperature-volume diagram.

Despite the relatively high cycling temperature, no evidence of sintering can be observed. Additional evidence that no sintering occurred upon cycling is provided... 

A Diesel engine receives air at 27°C and 100 kPa. The compression ratio is 18. The amount of heat addition is 500kJ/kg. The mass of air contained in the cylinder is 0.0113 kg. Determine (1) the maximum cycle pressure and maximum cycle temperature, (2) the efficiency and work output, and (3) the MEP. Plot the sensitivity diagram of cycle efficiency versus compression ratio. 

A Diesel engine receives air at 60°F and 14.7 psia, the compression ratio is 16, the amount of heat addition is 800Btu/lbm, and the mass of air contained in the cylinder is 0.02 Ibm. Determine the maximum cycle temperature, heat added, heat removed, work added, work produced, net work produced, MEP, and efficiency of the cycle. 

An ideal Diesel engine receives air at 100 kPa and 25° C. The maximum cycle temperature is 1460°C and the compression ratio of the engine is 16. Determine (a) the work done during the compression process,... 

A Brayton engine receives air at 15psia and 70°F. The air mass rate of flow is 4.08 Ibm/sec. The discharge pressure of the compressor is 78psia. The maximum cycle temperature is 1740°F and the air turbine... 

An engine operates on an actual reheat open Brayton cycle (Fig. 4.15a)). The air enters the compressor at 60°F and 14.7 psia, and exits at 120psia. The maximum cycle temperature (at the exit of the combustion chamber) allowed due to material limitation is 2000°F. The exit pressure of the high-pressure turbine is 50 psia. The air is reheated to 2000° F, and the mass flow rate of air is 1 Ibm/sec. The exit pressure of the low-pressure turbine is 14.7 psia. The compressor efficiency is 86% and the turbine efficiency is 89%. Determine the power required for the compressor, the power produced by the first turbine, the rate of heat added in the reheater, the power produced by the second turbine, the net power produced, back-work ratio, and the... 

An engine operates on the actual regenerative Brayton cycle (Fig. 4.18a). Air enters the engine at 60°F and 14.7 psia. The maximum cycle temperature and the maximum pressure are 2000°F and 120 psia. The compressor efficiency is 85% and the turbine efficiency is 89%. The mass flow rate of air is 1 Ibm/sec. Determine the power required for the... 

Husbandry Light-dark cycle Temperature range Humidity range Housing during pre-study... 

At Arosa, Switzerland, where there are records back to 1926 (the longest data record available), the trend in annual mean 03 has been determined to be —(2.3 + 0.6)% per decade. When contributions due to the solar cycle, temperature, and stratospheric aerosol concentrations are taken into account, the trend is —(1.9 0.6)% per decade. However, the total measured column 03 includes both stratospheric and a smaller tropospheric contribution, and the latter has been increasing (see Chapters 14 and 16). This would tend to mask part of a decrease in stratospheric 03. Applying an estimate of the increase in tropospheric ozone gives a trend in stratospheric 03 of - (3.0 + 0.6)% per decade at Arosa (Staehelin et al., 1998b). 

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