Problem HY.2 Questions
team_name
date
0. What adiabatic efficiency and power in kilowatts are required to compress an equimolar
mixture of n-hexane and n-octane from 25°C and 1 atm to 40°C and 400 atm? This liquid
mixture is flowing at 100 lb-moles per hour.
The adiabatic efficiency is _________% and the power is _________ kW.
1. Which HYSYS pump simulation algorithm (pumpa, pumpb, etc. in Appendix E) would you use to
solve this problem? What are the given variables and their values? What are the calculated
variables and their values?
 ____, n
E
, Z E , ____, ____   pump___ TI , PI , nI , Z I ,
Given Variables
TI  25 C
____, ____ 
Calculated Variables
__  1 atm
PI  1 atm
nE  100 lbmol / h
nI  100 lbmol / h
Z E  0.5, 0.5
Z I  0.5, 0.5
__  _______
__  _______
__  _______
__  _______
If a consistency error occurs, then you forgot to delete the efficiency value.
2. After you examine the process states (i.e., the temperature, pressure, flow rate, and composition) of the
inlet and exit streams, please answer the following questions.
Why does the exit temperature increase slightly?
Electrical and mechanical __________________________.
What is unique about the total molar flow rate and composition?
Both the total molar flow rate and composition remain ________________.
What equations in the math model and steps in the algorithm reflect it?
Math Model:
Math Algorithm:
1
____  ____  0
 2  nI  ____  nE  ____  0
Steps ___ and ___ in “pumpe”.
What assumptions support this uniqueness?
No __________________.
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for j  1, 2,
, nc
Problem HY.2 Questions
team_name
date
What are the operating conditions that would invalidate each assumption?
Assumption
Invalidation
continuous process
steady state
no chemical reaction
neglect KE change
neglect PE change
5. adiabatic
6. incompressible liquid
_____ inlet or outlet stream
total flow out is less than the __________
a chemical reaction _____ within the pump
inlet and outlet pipe diameters are _______
inlet and outlet pipe heights are _________
significant heat ______ to the surroundings
when liquid is significantly ____________
1.
2.
3.
4.
3. What is the ideal work expressed in units of horsepower?
 Wideal
 ___
 

  100

1 hp
1000 W
 _____ 


 100  _____ W 1 kW
Wideal   ______ kW  
 ______ hp
4. In the math algorithm, what variables are only functions of the material state ( i.e., the temperature,
pressure, and composition)
of the liquid?
 I , _____, and _____
5. What does the assumption of “adiabatic process” imply? Is this a valid assumption?
No ______________ to the surroundings. Yes, its value is small compared to the work term.
6. What is the energy relative imbalance (%RIB)? Show your calculations. The energy %RIB
equals 100*(energy flow in – energy flow out) / (energy flow in).
% RIBEB 
___________
Ein
 100
  _________ kJ/h  -  _________ kJ/h   _________ kJ/h 
  100
 _________ kJ/h 


% RIBEB  _________
% RIBEB  
Each energy flow value was obtained by copying it from HYSYS and pasting it here.
In the HYSYS software, the Mass/Energy Balance page within the Flowsheet/Flowsheet Summary
menu provides the relative imbalances for material and energy.
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