Is it possible to install APK file if more than one emulators/devices are connected

Yes, you can install an apk on a particular device.

In command, type:

adb devices
// list of devices and its unique ID...

Then type:

adb -s "<deviceIDfromlist>" install "<path-to-apk>"

Step 1: Get the device Ids of all connected device

adb devices

Step 2: Install to a particular device you want to install

adb -s deviceId install path+apk

Example:

Step 1:

C:\Android\android-sdks\platform-tools>adb devices

List of devices attached emulator-5554 device 014FD87107021017
device

Step 2:

C:\Android\android-sdks\platform-tools>adb -s 014FD87107021017 install C:\Users\
user\Documents\appname.apk

Use the following scripts to install apk on multiple devices/emulators.

    for SERIAL in $(adb devices | grep -v List | cut -f 1);
    do adb -s $SERIAL install -r /path/to/product.apk;
    done

Remove -r if you are not reinstalling the apk. Also you can replace "install -r /path/to/product.apk" to other adb commands like working on one single device.

It works for me on real devices but I believe it should also works for emulators.