765
Compared to conventional plate fin heat exchangers , nearly 25 % improvement in heat transfer density— the ratio between heat duty and mass ( Q/m ) —was noted at a coefficient of performance ( COP ) of 62 .
 machine or equipment: heat exchangers; concept or principle: heat transfer; concept or principle: heat; concept or principle: performance
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 machine or equipment: heat exchangers; concept or principle: heat transfer; concept or principle: heat; concept or principle: performance