Hi Kanth,

Please follow given below steps and link with the help of below steps and link you can solve your problem, it may be helpful to you. 

1. Developer Edition: Yes there is a limit of 10/day to use single email method to send emails. But you can use it to send more than 10 email/day for that you need to attach more than person email id and then use send email method of single email class to send email in bulk.

The limit is to use sendEmail method 10 times in a day not to send only 10 email/day. To send more than 10 emails you need to create a logic which sends email to more than one person by using single call or send email  method by adding email it to setToAddresses[] method, setCcAddresses[], etc

2. Single Email limit and mass email limit Of an enterprise Org
500 for mass.

3. Single Email Limit and mass email limit Of a Professional Org
250 for mass.

For more information follow below link :
Link: http://resources.docs.salesforce.com/220/13/en-us/sfdc/pdf/salesforce_app_limits_cheatsheet.pdf
Link: https://salesforce.stackexchange.com/questions/95293/email-limits-in-salesforce

I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too.

Thanks and Regards,
Deepali Kulshrestha