I know it is possible to send ComponentArray but here i need to pass a dummy array to create a collection loop in DWT. Am unable to pass dummy componentArray as it throws item not found error. Any hints is highly appreciated.
No, unfortunately what you're trying to do is not possible in DWT/TEL. As you've found, custom & dummy arrays don't work in the package.
I'd suggest that you create the desired output markup in a C# TBB (either in the one where you're creating your array of data, or by serialising the data and then de-serialising it in a subsequent TBB) and pushing that HTML snippet as a string into the package. Then just use a simple
@@MyCustomStringName@@ to pull that into the resulting output in your DWT.
As Alvin mentions in the comments, there is some possibility to create and loop over simple string arrays. I'm not sure if this is fully supported (i.e. "upgrade-proof").
You can create a "Dummy Component Array" that will be used only as counter for the values that are previously added to the package with number suffix. This way you use Dummy Component Array just for DWT Repeater and it's TemplateRepeatIndex to create an exact name of package you want to retrieve.
<!-- TemplateBeginRepeat name="MyDummyArray" -->
<!-- TemplateEndRepeat -->
For the "Dummy Component Array" you can use any dummy TCMURI, they can all be tcm:0-0-0.
This way was already explained\ in post what-can-we-loop-over-in-dwt-layout-template-building-blocks