Water outlet temperature

Ejector (steam-jet) refrigeration systems are used for similar apph-cations, when chilled water-outlet temperature is relatively high, when relatively cool condensing water and cheap steam at 7 bar are available, and for similar high duties (0.3-5 MW). Even though these systems usually have low first and maintenance costs, there are not many steam-jet systems running. 

The condensing water temperature has an important effect on steam rate per refrigeration effecd, rapidly decreasing with colder condenser cooling water. Figure 11-108 presents data on steam rate versus condenser water inlet for given chiUed-water outlet temperatures and steam pressure. 

Chilled-water temperature. As the chilled-water outlet temperature decreases, the ratio of steam/refrigeration effect decreases, thus increasing condensing temperatures and/or increasing the con-densing-water requirements. 

Thermocycle capacity is a function of the temperature difference between the chilled-water outlet temperature leaving the cooler and the inlet condenser water. The cycle finally stops when these two temperatures approach each other and there is not sufficient vapor pressure difference to permit flow between the heat exchangers. 

Approach the temperature difference between the tower cold water outlet temperature and the wet bulb temperature of the air. The smaller the approach the more difficult the coolingjob, and the larger the required tower. For a fixed cold water temperatiure, changing the wet bulb temperature by one degree can make a significant difference in tower requirements. Usually an approach of 5°F is considered minimum. 

Rapid fouling caused by water outlet temperature above 125T... 

The proportional controller is reverse-acting so that the control valve throttles down to reduce steam flow as the hot water outlet temperature increases the control valve will open further to increase steam flow as the water temperature decreases. 

The response curves shown in Figure 24 illustrate only the demand and the measured variable which represents the hot water outlet temperature. 

Let s say that the cooling-water outlet temperature from the condenser was 140°F. This is bad. The calcium carbonates in the cooling water will begin to deposit, as water-hardness deposits, inside the tubes. It is best to keep the cooling-water outlet temperature below 125°F, to retard such deposits. Increasing the pumparound heat removal will lower the cooling-water outlet temperature. 

Throttling on the cooling water works fine, as far as pressure control is concerned. But, if the water flow is restricted too much, the cooling-water outlet temperature may exceed 125 to 135°F. In this tempera-... 

First, I tried opening valve A. Just as the chief operator said, the cooling-water outlet temperature increased, proving that water flow was reduced. Next, I checked the pressure at bleeder B it was 12 in Hg. The pressure was so low at this point because of... 

I now observed that the surface condenser cooling-water outlet temperature had increased from 100 to 135°F. This is a sign of loss of cooling-water flow. As none of the other water coolers in the plant had been affected, I concluded that the cooling-water inlet to my surface condenser was partly plugged. 

Prepare an enthalpy-temperature diagram. Select the exit air enthalpy so that the slope of the line for the air enthalpy is equal to the slope of the curve for the enthalpy of saturated air at the water outlet temperature. 

With no heat being transferred through the jacket, an accurate prediction of the jacket water outlet temperature should be possible by knowing the history of the jacket inlet temperature and the mixing characteristics of the jacket. Therefore, the difference between the actual and predicted outlet temperatures multiplied by the flow rate and specific heat of the water should also equal Q. 

A verag evafae of% n2 °Jj e actUal Qnd predicted jacket water outlet temperatures. 

T. = jacket water inlet temperature - C Tout= 3acket water outlet temperature - C T = reactor temperature - °C tR = time... 

Override controls are used to protect against fouling of the heat transfer surfaces, when the water outlet temperature exceeds 50°C (122°F) or to prevent... 

A condenser consists of 30 rows of parallel pipes of outer diameter 230 mm and thickness 1.3 mm with 40 pipes, each 2 m long in each row. Water, at an inlet temperature of 283 K, flows through the pipes at 1 m/s and steam at 372 K condenses on the outside of the pipes. There is a layer of scale 0.25 mm thick of thermal conductivity 2.1 W/m K on the inside of the pipes. Taking the coefficients of heat transfer on the water side as 4.0 and on the steam side as 8.5 kW/m2 K, calculate the water outlet temperature and the total mass flow of steam condensed. The latent heat of steam at 372 K is 2250 kJ/kg. The density of water is 1000 kg/m3. 

If the water outlet temperature is limited to 310 K, then the mass flow of water is given by ... 

Arrangements with 4 and 6 tube side passes require water outlet temperatures in excess of the condensing temperature and are clearly not possible. With 2 tube side passes, T = 327.2 K at which severe scaling would result and hence the proposed unit would consist of one tube side pass and a tube length of 3.05 m. 

The maximum water outlet temperature to minimise scaling is 320 K and a value of 300 K will be selected. Thus the water flow is given by ... 

Saturation temperature of Freon-11 = 40°C Cooling-water inlet temperature = 32°C Cooling-water outlet temperature = 37°C hi (cooling-water side) = 8,000 kcal/(m )(h)(°C)... 

Water at 1500 kg/h and lO C enters a 10-mm diameter smooUi tube whose wall temperature is maintained at 49°C. Calculate (a) the tube length necessary to heat the water to 40°C, and (i>) the water outlet temperature if the tube length is doubled. Assume average water properties to be the same as in (n). 

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