Multi_R_Designer Tutorial

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1) Before starting a new query, the default units must be changed from SI to English units. From Tools, select the Preferences option and then the Unit tab. The following dialog window will be presented to the user. Three default system have been implemented in Multi_R_Designer, namely SI, English and CGS unit systems. Press the English button and all units will be changed into English units. Press Apply.
 

2) Start a new project by selecting Start new query .
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3) Apply the following problem specifications as described in the problem statement.

• First, select the Heat transfer tab and check the box related to Wall heat transfer coefficient, then Execute. A total of  507 data sets are extracted from the integrated databank. Then, select the Wall heat transfer coefficient corresponding pen  in the Value field. The following dialog window attests that the minimum-maximum range correspond to 48.42-4930.1 BTU/hr/ft ²/R. Write [300,1600] in the corresponding entry in order to satisfy the user's specification. Press OK, then Execute. A total of 279 data sets satisfies these conditions.

• Select the Gas tab and check the Gas density box. Then, select the Wall heat transfer coefficient corresponding pen  in the Value field. Write [0.1, 0.3] in the corresponding entry in order to satisfy the gas density specifications. Press OK, then Execute. A total of 157 data sets from Purwasasmita (1985) (Publication 4 in ) are extracted.

• In the Liquid tab, check the Liquid thermal conductivity box. Then, select the corresponding pen  in the Value field and write 0.65 in the <= option. Press OK, then Execute.

4) In order to ease the analysis on the liquid viscosity effect, a packing type and liquid mass flow rate will be set. Consequently, select the Reactor tab, check the Packing type box and then choose Beads from the corresponding combo list, Execute (Search results: 81 lines).

5) Thereafter, select the Operating conditions tab, check the Liquid mass flow rate box and enter 15000 +/- 20% in the appropriate boxes. Press OK, then Execute. A total of 29 values on h_w will be used to analyse the effect of liquid viscosity.
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Comment: Lower extension percentages (i.e. 5% instead of 20%) would produce an empty search result list since no liquid mass flow rate from the 81 data sets would be involved in the corresponding range of 14250-15750 (15000 plus/minus 5%) lb/ft²hr. A warning message appears in those situations.
 

6) Select the Plot button . In the Horizontal axis panel, choose Gas mass flow rate (Operating conditions: Gas mass flow rate). In the Vertical axis panel, choose Experimental (Heat transfer: Wall heat transfer coefficient: Experimental). In the Advanced panel, select Liquid viscosity (Liquid: Liquid viscosity) as the discriminate. Press OK. The following diagram will be created.
 
 

7) Select the Discriminate series button  and check the Value discrimination option. Write 100 in the Number of classes box. Press OK.
 

CONCLUSION: Only a general conclusion can be drawn from the plot. It shows that high liquid viscosities decrease the heat transfer coefficient at the reactor's wall (h_w) to a relatively large extent at least between viscosities of 3-10 lb/ft/hr. However, it seems that a limit is reached at ca. 12 lb/ft/hr where an increase in the liquid viscosity does not influence anymore h_w. For better heat transfer capacity, low viscosity liquids seems more suited than high viscosity liquids for example.

Multi_R_Designer Tutorial