Question

To compare between different desalination system different criteria have been used such as: Performance Ration (PR), Gain Output Ratio (GOR), Specific Energy Consumption (kWh/m3 ) and Unit Product Cost ($/m3 ). Define each one and on your opinion which criteria are considered most useful?

Answer 1

Performance Ratio (PR):

• It is defined as the ratio of the distillate mass to that of input energy.
• In metric units, it can be defined as the number of kg of water per MJ of heat input
• In British units, it can be defined as the number of pounds of water per 1000 Btu energy input.

Gained Output Ratio (GOR):

• It is a dimensionless ratio which is defined either as a mass ratio or an energy ratio. As an energy ratio, it is usually defined as the ratio of the total latent heat of evaporation of the product water to the input thermal energy
• It effectively uses the total heat content of the input steam, rather than the heat transferred as it ignores the heat content of the product
• The GOR also does not take into account any system efficiencies such as boiler efficiency, or heat losses through piping from the heat source.

Specific Energy Consumption:

• It is the energy consumed per unit volume of steam

Unit Production Cost:

• It is defined as the cost incurred while producing unit volume of water

Overall all the above four parameters are the performance metrics each have their own meaning. In my opinion all are inter related that means if we optimize any one of the above the others will be automatically optimized.