Mostafa Bayrami - Sustainable Management of Natural Resources and Environment Research Group, Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Viet Nam
Hakimeh Morabbi Heravi - Department of Statistics, University of Bojnord
Amir Alipour Yengejeh - Department of Statistics, University of Florida, USA

Regression analysis is a statistical process that can be used to estimate relationships among variables. This methodology involves various techniques to analyze the specific and unique variables, with a focus on the relationship between the dependent variable and one or more independent ones. In the present work, firstly, the fully fuzzy regression equation is converted to a linear fully fuzzy framework. Considering the least-squares approach, a model based on matrices to solve a system of equations to solve fully fuzzy linear regression using triangular fuzzy numbers for inputs and outputs .The present paper first validates the proposed model with a specific function and then evaluates the total heat transfer coefficient of a helical double-pipe heat exchanger with two inputs of inner Dean number and the annulus Dean number as a case study.

Helicoidal heat exchanger; Overall heat transfer coefficient; Linear regression model; Fully fuzzy matrix equations; Triangular fuzzy numbers