# What is your understanding of ventilation on demand and what relevance does it have for the mining industry?

there is one major project which is to design a suitable cooling system to cool air for air conditioning purpose by following criteria include diagram and chart, secondly other is write a report for how the ventilation in mine work as required and finally third two mathematically question need to be done.

thanks

Questions:

1:

Students are to write a report to answer the following:

What is your understanding of ventilation on demand and what relevance does it have for the mining industry?
For a mine that you work at or can gain information from what would be the impact of ventilation on demand to the operation. Students should consider the effect on both production and development airflows. However a full network analysis determining the overall system impact is not required.
Students should report on the infrastructure and any other operational changes that would be required to implement ventilation on demand at the site, eg control and monitoring requirements.
The expectation is of a report in a standard engineering format. All assumptions must be detailed and justified and must comply with any mine legislation. Students are also encouraged to detail any further research they believe is required to enable such a system to be developed.

2:

A steel pipe has an internal diameter of 150mm and an outside diameter of 160mm. The pipe carries water at a temperature of 10°C flowing at a velocity of 0.5 m/s. The air surrounding the pipe has a dry bulb temperature of 27°C. The air flow’s over the pipe with a velocity of 3 m/s. If the pipe is covered by insulation of 30mm thickness with a thermal conductivity of 0.035 W/m°, determine:

(a) The UA factor for 1m length of insulated pipe,

(b) The rate of heat gain by the water per m of pipe

(c) The temperature of the inner and outer surfaces of the pipe and the temperature of the outer surface of the insulation

(Note ksteel = 45 W/m°C, hc inside pipe = 1400 W/m2°C, hc outside insulation = 18 W/m2°C and radiative heat transfer coefficient outside insulation hr = 6.1 W/m2°C)

3:

A basic vapour compression refrigeration system is using refrigerant R12 .The evaporator temperature is 0°C and the condenser

temperature is 55°C .The isentropic efficiency of the compressor is 80%. Observations made on the chilled water circuit to the evaporator indicate that the cooling duty is 1800 kW. Assuming the refrigerant enters the compressor as a saturated vapour and leaves the condenser as a saturated liquid detail the necessary calculations and then plot the cycle on the R12 pressure/specific enthalpy diagram provided. Also calculate:

(a) The power input to the compressor;

(b) The rate of heat removal in the condenser;

(c) The actual coefficient of performance;

(d) The Carnot COP;

(e) The cycle efficiency.

Discuss briefly how the COP of this plant might be improved and illustrate the benefits by providing a freehand sketch of the modified refrigeration cycle on a appropriate property diagram.

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