I understand that a "patchy consolidation" can be indicative of pneumonia. but could someone have a patchy consolidation if he also had,for instance, copd & bilateral pleural effusions?

Yes it can be: Some one with COPD and bilateral effusion can also have Patchy Consolidation.It may be due to a co existing Pneumonia or it may be due to pulmonary edema(fluid in the lungs) or Atelectasis(Collapse of Lung)That is why we always say to medical students and residents,that we never treat the xray findings.But first History/Physical and xray in the context of Patients clinical presentation

Yes: In short, yes. Patchy consolidations is somewhat of a "non-specific" term. Meaning that it describes an appearance of the x-ray rather than being a diagnosis in itself. The consolidations could made up of numerous things such as mucous or fluid and usually describe fluid inside the airways rather than outside the lung tissue itself, like in a pleural effusion.