This is almost certainly not someone in the personnel department, and it is probably not a department head either. It is most likely to be the person who will actually supervise you once you start work. Call the company to make sure you have the right name. And spell it correctly. The opening should appeal to the reader.
Cover letters are sales letters.
Sales are made after you capture a person's attention. You capture the reader's attention most easily by talking about the company rather than yourself. Mention projects under development, recent awards, or favorable comments recently published about the company. You can find such information in the business press, including the business section of local newspapers and the many magazines that are devoted to particular industries. If you are answering an ad, you may mention it.