Amid weeks of intense heat across Europe, a niche Chinese air conditioner has become one of the hardest-to-buy products in the region this summer, selling out within just a few weeks.A type of portable air conditioner (AC) made by Chinese home appliance giant Midea – the PortaSplit – has sold out across multiple e-commerce platforms as temperatures in parts of Europe have exceeded 40 degrees Celsius (104 degrees Fahrenheit).The unit has gained traction in the region, in part, because it...