31 Jan 2015
11 Dec 2014
This is a brief review written by us of above mention article taken from sciencedirect.com
Draught drinks cooling system can be found in bars, restaurants and clubs etc which work 24 hours a day and 7 days a week. The basic draught drinks cooling system consist of two sub systems one is refrigeration subsystem and other is drink subsystem. The refrigeration subsystem consist of compressor, condenser, condenser fan, filter, expansion valve( capillary tube), internal heat exchanger and evaporator while drink subsystem consist of beverage coil, column and tap. Other than this system has a tank having water in it. Evaporator and beverage coil both are also placed in the tank.
During working evaporator absorb heat from water and drop its temperature to 0 degree C this water absorb heat from the beverage in beverage coil and drops its temperature to 3 degree C. Beverage in the column and tap is exposed to ambient temperature where its temperature can drop so to maintain a constant temperature water from the tank is circulated in the column and tap section with the help of a pump. In ideal working compressor work for 5 min and them switch of 23 min. In this 23 min ice in the tank melt and then in 5 min compressor restore it so the one cycle of refrigeration system is of 28 min. this can vary from on application to other like in small restaurant in peek consumption it is 30 min and in bars it is up to 73 min.
Experimental setup and Calculations
To measure the temperature and pressure, sensors are placed before and after the compressor, condenser, filter, expansion valve, internal heat exchanger and evaporator. When system start working we got the temperature and pressure readings and base on this information we made our calculation. When work done by compressor is known then we can find out mass flow rate and then with the help of the formula
and steam table we can find the heat absorb or rejected by the condenser and expansion valve. Then with help of 2nd law of thermodynamic we can find the heat absorbed by the evaporator. Now we can find out the overall coefficient of performance of the refrigeration system.
In beverage cooling system there are three places from where ice can gain heat one is the outer atmosphere second is the beverage itself and the third is stirrer and pump installed inside the tank. Maximum heat absorb by the ice is when there is maximum consumption of beverage which depends upon the designing limitation of the machine. Power needed to cool down the beverage when there is maximum consumption is
Heat gain by the ice from the outer atmosphere came through lateral walls, bottom wall and top wall. Resistance given by each wall in heat flow is depending upon its thickness, area and thermal conductivity.
There are some improvements needed for this system like replacement of low efficient internal heat exchanger (having only 15% efficiency) by more efficient heat exchanger. System work 24 hours a day but when bar is closed there is consumption of energy for 5 min after every 23 min with no profit or beverage output solution is stop the machine when bar is closed but the problem is when bar is reopen system will take time to restore ice in tank. After experiments it is concluded that a real time clock must be integrated with the system so that sensor start the compressor time before the bar is open.
In this analysis of a cooling system designed for the cooling of the beverage drinks we have used pressure and temperature sensors and EES software for simulation and after many laboratory test we find that the COP of the refrigeration system was good about 3.14 but for the aver all system it was very low about 9.57E-2 which need to be improve. We have suggested the use of more efficient components as well as introducing a new real clock subsystem in the system to save energy.
8 Sep 2014
Nestler boiler is a horizontal axis boiler and belongs from fire tube types of boilers. Shell of nestle boiler consist of two thick mild steel plates. A large number of fire tubes are fitted in between the steel plates. A bigger diameter furnace tube extending from burner end to other end is used for carrying hot flue gases from one smoke box to the other smoke box. At the rear end smoke box chimney is provided for rejection of exhaust gases. Fuel which is used for the burning is a highely viscous fluid which is firstly heated up to 80 C and then supplied for the burning purpose. Nestler boiler can deliver the steam upto 10-11 bar pressure.
Parts of Nestler Boiler
- Pressure gauge
- Stop valve
- Safety valve
- Rear end smoke box
- Centrifugal pump
- Blow off cock
- Flue tube
- Front end sample box
- Fusible plug
Working of Nestler Boiler
Fuel and high pressure air is mixed to produce the air fuel mixture which is burn in o produce the hot gases. Hot gases move through the furnace tube and enter the rear end smoke box of the nestler boiler. From the rear end smoke box hot gases enter into the fire tube which is surrounded by the liquid. Hot gases transfer their heat to the liquid and move forward into the front end sample smoke box from there finally hot gases moves toward the chimney from where they are eliminated into the atmosphere. Steam produce as the result of heat transfer between hot gases and water is collected into the steam chamber above.
6 Sep 2014
They are the horizontal boiler and belong from the fire tube class of boilers. Locomotives boiler are divided into three main parts smoke box, shell box and fire box.
Parts of locomotive boilers
- Ash pit
- Fire box
- Fire hole
- Fire brick arch
- Fusible plug
- Operating rod
- Steam whistle
- Safety valve
- Super heating tube
- Steam pipe
- Steam header
- Smoke box
- Blast pipe
- Super heated steam out let
Working of locomotive boiler
Fuel is place on the grate where it is burned to produce the hot gases. Fire hole is used to feed the fuel. Hot gases which are produce as a result of fuel burning are diverted into fire tube with the help of fire brick arch. Steam produce is collected is the steam drum place at the top of the shell. As shown the wet steam goes through inlet headers of super heater and after passing through tubes, it returns to the outlet header of super heater and is taken out for steam engine. For the cleaning and maintenance of the complete boiler a door is provided at the side of the smoke box. Chimney is completely eliminated in locomotive boilers because they are always in motion
Application of locomotive boilers
Locomotive boilers are used to give power in following machinery
- Steam railway engine
- Marine steam engine
These boilers were invented for getting steam to run a steam engine used in locomotives.